SCIENCE VACATIONS H.W.

CHEMICAL REACTIONS AND EQUATIONS
SECTION A
1
Based on the video solve the questions that follows:
a (i) A chemical equation represent the _______ that actually takes place.
(ii) 1molecule of H2SO4 contains 2 Hydrogen , 1 Sulphur and 4 Oxygen atoms What does 1 molecule of Ca(OH)2 contain ?
(iii) Complete the following sentences:
 Chemical equation are balanced to satisfy the law of ________
 The number and type of all _______must be the same on both sides of the reaction arrow.
(iv) Write the following statement in the form of a balanced chemical equation :
One atom of sodium combines with one molecule of oxygen to give one molecule of sodium oxide.
(v) Construct chemical equation from the following:

2

(vi) Balance the following chemical equation:
 ____ N2 + ____ H2 → ____ NH3
 ____ KClO3 → ____ KCl + ____ O2
 ____ Pb(OH)2 + ____ HCl → ____ H2O + ____ PbCl2
 ____ AlBr3 + ____ K2SO4 → ____ KBr + ____ Al2(SO4)3
 ____ CH4 + ____ O2 → ____ CO2 + ____ H2O
 ____ Na + ____ H2O → ____ NaOH + ____H2
b
(i) In a chemical reaction ,one reactant breaks up to give two or more products.Name the reaction.
(ii) Identify the type of reaction and name the cations and anions.
P+T- + S+N- → P+N- + S+T-
(iii) You are provided with two ionic compounds-Sodium sulphate( Na2SO4) and barium chloride(BaCl2).
 Identify the positive ion(cations)and negative ions(anions) in each.
 Identify the type of reaction that will occur ,if you combine the above two reactants.
 write chemical equation for the chemical reaction taking place.
(iv) What do you mean by’ activity series of metals’
(v) What type of chemical reactions are represented by the following equations?
 A + BC → AC + B
 A + B → C
 X → Y + Z
 A2O3 + 2B → B2O3 + 2A
3
(vi)The following equations are based on synthesis or direct combination.
Complete and balance them
 Fe + Cl2 
 P2O5 + H2O 
 Fe + O2 
 N2 + H2 
 Al + N2 
 K2O + H2O 
 SO2 + H2O 
c A magnesium ribbon is burnt in oxygen to give a white compound ‘X’ accompanied by
emission of light. If the burning ribbon is now placed in an atmosphere of nitrogen, it
continues to burn and form a compound ‘Y’
 Write the chemical formula of ‘X’ and ‘Y’.
 Write a balanced chemical equation, when ‘X’ is dissolved in water.
(i) Below are given two chemical reactions:
 H2 (g) + Cl2(g) → 2HCl (g)
 2AgCl(s) → 2Ag (s) + Cl2(g)
Which is a decomposition reaction and which is a combination reaction.
(ii) Calcium carbonate when heated gives rise to calcium oxide and carbon
dioxide.What type of reaction is this?What are the reactants and what
are the products?
(iii) Group the ions in the following reaction to depict a decomposition reaction.
 Na2SO4 (aq) + BaCl2 (aq) →
(iv) Complete the following double displacement reaction .
 KI + Pb(NO3)2 →
 Is there any precipitate formed?
 If any precipitate is formed , write the colour of the precipitate.
(v)Identify the reaction type from the following pictorial representation. How is this
different from double displacement reaction?

4
(vi) The process which involves gain of hydrogen or loss of oxygen is called ____________
(vii) What is reduction?
(viii) A ____________ is a substance which give hydrogen or gains oxygen.
2
Matter undergoes certain changes as a result of the application of energy. Glaciers melt in summer and rivers freeze in winter. Water from sea evaporates to form vapours , which forms clouds and then condenses to form rain.
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reaction can be either spontaneous, requiring no input of energy or non-spontaneous, often coming about only after the input of some type of energy i.e heat, light or electricity. Chemical reactions encompass changes that strictly involve the motion of electrons in the forming and breaking of chemical bonds, although the general concept o f a chemical reaction in particular the notion of a chemical equation, is applicable to transformation of elementary particles as well as nuclear reactions.
The substance/substances initially involve in a chemical reaction are called reactants. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants.
a
Fill in the blanks:
(i) Chemical reaction are the process in which ______ substances with new _____ are formed.
(ii) In chemical reaction the _____ obtained must have different properties from that of _____.
(iii) In a chemical reaction there must be either an _____ or an _____ of heat.
b
State true or false:
(i) In chemical reaction product obtained had same properties as that of a reactant.
(ii) In chemical reaction there is always a loss of matter.
c
What are chemical reactions?
d
What are reactants?
e
What do chemical reactions yield?
5
SECTION B
Choose the correct alternative:
1
Which amongst the following does not hold good for a balanced chemical equation?
a
Obeys law of conservation of mass
b
Has equal number of atoms of each element on both the sides of the equation
c
Mass of the reactants equal the mass of the product
d
Mass of the reactants is greater than mass of the products
2
Which amongst the following is used for white washing?
a
CaO mixed with water
b
CaSO4 mixed with water
c
Ca(OH)2 mixed with water
d
CaCO3mixed with water
3
White silver chloride changes to grey in sunlight because of the formation of silver metal along with the evolution of chlorine gas. Identify the chemical equation that gives a correct representation of the process.
a
2AgCl → 2Ag + Cl2
b
AgCl → Ag + Cl2
c
2Ag + Cl2 → 2AgCl
d
Ag + Cl2 → 2AgCl
4
In the following set up, the gas evolved turns lime water milky. Identify ‘X’.

a
dilute HCl
b
water
c
NaOH solution
d
calcium hydroxide
5
The given equation represents the reaction of sodium metal with water.
Sodium + Water→ Sodium hydroxide + Hydrogen
Which of the following chemical equations represents a complete balanced chemical
equation for the given word equation?
6
a
2Na(s) + H2O → 2 NaOH(aq) + H2(g)
b
Na(s) + 2H2O → NaOH(aq) +2H2(g)
c
2Na(s) + 2H3O → 2NaOH(aq) + 2H2(g)
d
2Na(s) + 2H2O → 2NaOH(aq) + H2(g)
6
Four students were asked to observe the effect of heat on lead nitrate crystals. The teacher provided them with test tube holders, test tubes and solid lead nitrate, The students then started heating lead nitrate as shown below. The teacher stopped three of them for using the wrong procedure.
The correct way of heating is

a
I
b
II
c
III
d
IV
7
Ritika noted the initial colour of the solutions in beakers I, II , III and IV. After inserting zinc rods in each solution and leaving undisturbed for two hours, she noted the color of each solution again. Mark the beaker in which colour change is observed?

a
I and II
b
II and III
c
III and IV
d
I and IV
8
Steps taken for performing the reaction between copper sulphate and iron are:
(i)prepare copper sulphate solution by dissolving a few crystals of copper sulphate in water.
(ii) put some iron nails in it.
(iii)leave it for five minutes.
(iv)observe the change in the colour of the solution
(v)take out the iron nails and observe for any deposit on it.
The result of the above experiment is not as expected. Identify the step that has been missed out.
a
heat copper sulphate solution before putting iron nails.
b
cool copper sulphate solution before putting iron nails.
c
rub the iron nails with sand paper.
d
close the test tube with a cork.
9
Study the following chemical equations:
Pb2+ + 2e-
Pb 2Br- - 2e-
Br2
(i) Lead ions gain electrons to form lead atoms
(ii) Bromide ions lose electrons to form bromine atoms.
(iii)The bromine atoms combine to form molecules of bromine gas.
(iv) Lead ions lose electrons to form lead atoms.
The correct statements for electrolysis of lead bromide is:
a
(i) , (ii) and (iii)
b
(i) , (ii) and (iv)
c
(i) , (iii) and (iv)
d
(ii) , (iii) and (iv)
10
Students were asked to study reaction between barium chloride and sodium sulphate.Four different reports of the experiment are given below. Choose the correct one.
S.No.
Procedure
Observation
A
Mixed powder of barium chloride and sodium sulphate
The colour of the mixture changes to yellow
B
Mixed solutions of barium chloride and sodium sulphate
Thick white precipitate is formed
C
Add solution of barium chloride to sodium sulphate powder
Solution becomes turbid
D
Add solution of barium chloride to sodium sulphate solution
No change is observed
Which one is correctly matched among the following?
a
B
b
C
c
D
d
A
8
11
Complete the following statement by choosing correct type of reaction for X and Y.
Statement 1: The heating of lead nitrate is an example of 'x' reaction
Statement 2: The burning of magnesium is an example of 'y' reaction.”
a
X
Y
combination
decomposition
b
X
Y
decomposition
combination
c
X
Y
combination
displacement
d
X
Y
displacement
decomposition
12
In the given figure, the red brown gas evolved is _______ .

a
Oxygen
b
Carbon dioxide
c
Nitrogen dioxide
d
Carbon monoxide
13
Which of the following changes will result in a substance with new chemical properties?
a
baking a cake
b
melting of ice cream
c
chopping a bunch of spinach
d
cooling a bottle of water in the fridge
14
Consider the following processes.
(i) rusting of iron
(ii) anti biotics fighting an infection
(iii)digestion of food in the stomach
(iv)photosynthesis in plants
(v)rising of cake in an oven
Which of the above are chemical interactions?
a
1 only
b
1 and 5 only
c
1,3 and 5 only
d
All- 1,2,3,4 and 5
9
15
Robinson discussed the gas -filled packet with his science teacher, and came to know that when the chips are packed, the air in the packets is replaced with nitrogen. Why are the packets filled with nitrogen?
a
Our body needs nitrogen and the chips absorb it.
b
Nitrogen is not a very reactive gas, so the chips remain fresh.
c
Nitrogen is not an inflammable gas, so it is safer to handle the packets.
d
Nitrogen contains only one type of atoms and is more hygienic than air.
16
Which chemical change corresponds to a reduction?
a
Calcium hydroxide reacts with acid waste gases from an industrial metal extraction process to form a harmless salt and water.
b
changing copper oxide into copper in a smelter.
c
carbon monoxide reacts with iron oxide to form carbon dioxide.
d
Calcium carbonate forms calcium oxide and carbon dioxide in the blast furnace extraction of iron.
17
A compound P is taken in a flask flat bottomed flask as shown in figure. Dilute hydrochloric acid is added drop by drop. A gas Q is evolved which is then passed in a test tube containing R. A solid precipitates S is formed is frequently used in white washing. During white washing a layer of R is applied on the wall and it reacts with gas Q(present in air) to produce white shiny layer of S on the wall.P , Q , R and S respectively are _____.

a
P= Na2SO4 : Q= SO2 : R= Ca(OH)2 : S= CaSO4
b
P= Na2SO3 : Q= O2 : R= Ca(OH)2 : S= CaO
c
P= Na2CO3 : Q= O2 : R= Ca(OH)2 : S= CaCO3
d
P= Na2CO3 : Q= CO2 : R= Ca(OH)2 : S= CaCO3
18
Complete the following statement by substituting X and Y with correct options
“Corrosion and rancidity are the result of ‘x’ reaction of iron articles and oils/fats
respectively. Galvanization is done to prevent corrosion of iron articles and ‘y’ are
used to prevent rancidity of oils or fats.”
10
a
X
Y
displacement
oxidants
b
X
Y
oxidation
anti -oxidants
c
X
Y
displacement
anti -oxidants
d
X
Y
combination
anti -oxidants
19.
Complete the following statement by choosing correct type of reaction for X and Y.
Statement 1: Heating of potassium chlorate in the presence of manganese dioxide as a catalyst is an example of X reaction.
Statemenr2: Burning of natural gas is an example of Y reaction.
a
X
Y
displacement
endothermic
b
X
Y
combination
decomposition
c
X
Y
displacement
endothermic
d
X
Y
decomposition
exothermic
SECTION C
1.
What is meant by skeletal equation?.Write one example of decomposition reaction in the form of balanced equation. (sample paper 2010)
2.
You are provided with two containers made up of copper and aluminium. You are also provided with solutions of zinc chloride and HNO3.In which of the above containers these solutions can be kept.
11
3.
Why does magnesium powder react much more rapidly than magnesium ribbon with dilute sulphuric acid?
4.
On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue
green. Predict the new compound formed which imparts a blue green color to the solution.
5.
Balance and identify the type of reaction in the following chemical equation:
(OD 2008)(Sample paper 2011-12)
a
Fe (s) + H2O (g) → Fe3O4 (s) + H2 (g)
b
heat
CaCO3 (s) → CaO (s) + CO2 (g)
c
Zn (s) + H2SO4 → ZnSO4 (aq) H2 (g)
d
Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + NaCl (aq)
e
Fe (s) + CuSO4 (aq) → FeSO4 (aq) + Cu (s)
f
H2 (g) + O2 (g) → H2O (l)
g
HNO3 + Ca(OH)2 → Ca(NO3)2 + H2O
h
Al (s) + CuCl2 (aq) → AlCl3 (aq) + Cu(s)
6.
A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test tube. The evolved gas was then passed through lime water. What change would be observed in lime water? What will happen if excess of gas is passed through lime water? Write balanced chemical equations for all the changes observed
7.
A grey coloured metal ‘X’ is used for coating iron to prevent it from rusting.’X’ when dipped in iron sulphate solution , the solution changes to colourless and a greyish black metal ‘Y’ is formed .Identify ‘X’ and ‘Y’ and the type of reaction.
8.
What change in color is observed when white silver chloride is left exposed to sunlight? State the type of chemical reaction in this change.
12
OR
Why do we store silver chloride in dark coloured bottles?
9.
A substance ‘X’ is pale green coloured solid. It gets oxidised to reddish brown coloured solid, if kept in air for long time. On heating it forms reddish brown solid ‘Y’ along with two pungent smelling gases ‘A’ and ‘B’. ’A’ is anhydride of sulphurous acid and ‘B’ when dissolved in water forms sulphuric acid. Identify ‘X’, ‘Y’, ‘A’ and ‘B’.Name the type of reaction.
10.
A light sensitive compound ‘X’ of silver is used in black and white photography. On exposure to sunlight its colour changes to gray :
a
Identify ‘X’.
b
Write a chemical equation to express the above change .
c
Identify the type of chemical reaction.
11.
What is an oxidation reaction? Identify in the following reaction:
(a) the substance oxidized and (b) the substance reduced
.(Delhi 2008)(sample paper 2011-12)
ZnO + C → Zn + CO
CuO + H2 → Cu + H2O
12.
A silver article generally turns black when kept in open for a few days. The article when rubbed with tooth paste again starts shining.
a
Why do silver articles turn black when kept in open for few days? Name the phenomenon involved.
13
b
Name the black substance formed and give its chemical formula.
13.
a
When the powder of a common metal is heated in an open china dish, its colour turns black. However, when hydrogen is passed over the hot black substance so formed, it regains its original colour. Based on the above information answer the following questions: (OD 2010)
What type of chemical reaction takes place in each of the two given steps?
b
Name the metal initially taken in the powder form. Write balanced chemical equations for both reactions.
OR
A brown substance 'X' on heating in air forms a substance 'Y'. When hydrogen gas is passed over heated 'Y', it again changes back into 'X'
a Name the substance X and Y.
b Name the chemical processes occurring during both the changes. Write the chemical equations
14.
Observe the given figure and answer the following questions(OD 2005)

a Write the complete balanced reaction for the above.
b
Type of reaction involved.
c Is there any precipitate formed?
d If any precipitate formed, write the colour of the precipitate.

SECTION D
1
The diagram shows three calcium compounds.
Step 3
CaO CaCO3
Step I Step 2
Ca(OH)2
a Which compound is present in lime water?
b What is added to calcium oxide to carry out step 1.
c Which step occurs during the test for carbon dioxide?
2 After ten minutes of keeping the set up as shown in the figure, the colour of the iron
nail changes, what does this indicate?

a. Name the type of chemical reaction that takes
place between copper sulphate and iron nail.
_______________________________________
b. Which of the two metals involved in the given
process is more reactive?
_______________________________________
c. What change do you expect in the reaction
mixture if a copper wire is kept immersed
in an iron sulphate solution?
_______________________________________
_______________________________________
3 Observe the test tube ‘A’ and ‘B’ in the diagram given below and answer the following
questions

a. In which test tube will the reaction take place?
________________________________________
b. Name the type of reaction and write a balanced
equation for the reaction.
________________________________________
________________________________________
________________________________________
15
3
Study the following set up and answer the following:

a.Write the name and the chemical formula of the product formed.
___________________________________________
___________________________________________
b. State the two observations made in the experiment.
___________________________________________
___________________________________________
___________________________________________
4
Study the following activity and identify the following:

a. Type of reaction.
__________________________________________
b. Name the gas evolved in the above reaction.
__________________________________________
c. Do you observe any colour change in the above reaction? If yes, mention the colour change.
__________________________________________
__________________________________________
d. Name the colored substance formed.
__________________________________________
__________________________________________
5
The given set up shows the electrolysis of water taking place.

a
Identify the gases evolved at cathode and anode.
16
b
Why is the gas collected in one of the test tubes double the amount in the other? Name this gas.
c
Test these gases one by one by bringing a burning candle close to the mouth of the test tubes. What happens in each case?
6
Observe the following picture and do as directed:

a
What are the two conversions explained by the research student? Show with the help of a chemical equation.
17
b
How can chemical industries reduce their carbon emission?
c
What are the values depicted by Bhaduri and Lidija Siller?
QUESTIONS BANK
1.
What are the endothermic reactions? (OD 2005 )
Give an example of an endothermic reaction.(sample paper 2010)
2.
Why do we apply paint on iron articles?
"Oxidation and reduction processes occur simultaneously." Justify this statement with the help of an example. .(sample paper 2010)
3.
(a)With the help of a suitable example, explain Oxidation and Reduction in terms of gain or loss of oxygen. (b)What is meant by rancidity ?(sample paper 2011-12)
4.
Which one is a chemical change - fermentation of fruit juice or diluting fruit juice ?
5. Write observation with reaction for the following: 2 granulated zinc reacts with dil. Sulphuric acid.
6.
What is the role of a catalyst in a chemical reaction? (OD 2007)
7.
What happens when sodium sulphate and barium chloride solutions are mixed?
(OD 2005)
8. “Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate”. (sample paper 2010)
(a) Translate the above statement into a chemical equation
(b) State two types in which this reaction can be classified.
9.
Complete the following reactions and balance them: (Delhi 2006 )
Zn + H2SO4 →
Fe (s) + H2O (g) →
C6H12O6 (aq) +O2 (aq) →
18
DRILL EXERCISE
1
Balance the following reactions and indicate which of the six types of chemical reaction are being represented:
a
____ NaBr + ____ Ca(OH)2  ___ CaBr2 + ____ NaOH
Type of reaction:
b
____ NH3+ ____ H2SO4  ____ (NH4)2SO4
Type of reaction:
c
____ CH4 + ____ O2  ____ CO2 + ____ H2O
Type of reaction:
d
____ Pb + ____ H3PO4  ____ H2 + ____ Pb3(PO4)2
Type of reaction:
e
____ Li3N + ____ NH4NO3  ___ LiNO3 + ___ (NH4)3N
Type of reaction:
f
____ HBr + ___ Al(OH)3  ___ H2O + ___ AlBr3
Type of reaction:
2
Balance the following equations. Also write word equations for the same.
a
K + H2O KOH + H2
Word equation
b
Ca(NO3)2 CaO + O2 + NO2
Word equation
c
Pb3O4 + HCI (conc.) PbCl2 + H2O + Cl2
Word equation
d
NaNO3 NaNO2 + O2
Word equation
e
NH3 + PbO Pb + N2 + H2O
Word equation
f.
NH3 + Cl2 NH4Cl + N2
Word equation
g
NH3 + O2 NO + H2O
19
Word equation
h
FeCl3 + NaOH Fe(OH)3 + NaCl
Word equation
i
FeO + O2 Fe2O3
Word equation
j
NO2 + O2 + H2O HNO3
Word equation
k
P2O5 + H2O H3PO4
Word equation
l
FeCl2 + Cl2 FeCl3
Word equation
m
CuO + CO Cu + CO2
Word equation
3
Write the word equations below as chemical equations and balance
a
Zinc and lead (II) nitrate react to form zinc nitrate and lead.
b
Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas.
c
Sodium phosphate and calcium chloride react to form calcium phosphate and sodium
chloride.
d
Potassium metal and chlorine gas combine to form potassium chloride.
e
Aluminum and hydrochloric acid react to form aluminum chloride and hydrogen gas.
f
Calcium hydroxide and phosphoric acid react to form calcium phosphate and water.
g
Copper and sulfuric acid react to form copper (II) sulfate and water and sulfur dioxide.
20
h Reaction between ammonium hydroxide and sulphuric acid producing ammonium
sulphate and water.
i The reaction of a metal carbonate with dilute sulphuric acid to produce carbon dioxide.
j Reaction of Magnesium with hydrochloric acid.
k Dissolution of calcium oxide in water.
l Formation of ammonia.
4 The following equations are based on synthesis or direct combination. Complete and
balance them
a Fe + Cl2 
b P2O5 + H2O 
c Fe + O2 
d N2 + H2 
e Cu + Cl2 
f Al + N2 
g K2O + H2O 
h SO2 + H2O 
i H2 + S 
j H2 + Cl2 
5
Give balanced equations for the action of heat on:
a Lead (II) nitrate :
______________________________________________________________________
b
Iron(II) sulphate
_____________________________________________________________________
21
c
Silver oxide
______________________________________________________________________
d
Magnesium carbonate
______________________________________________________________________
e
Lead iodide
______________________________________________________________________
f
Sodium nitrate
______________________________________________________________________
6
The following equations are based on displacement. Complete and balance the
following equations
a Zn + HCl 
b
KBr + Cl2 
c
Cu + AgNO3 
d
Mg + H2SO4 
e
CuSO4 + Fe 
f
Nal + Cl2 
g
KCl + F2 
h
K + H2O 
i
Zn + FeCl2 
j
K + Ca(NO3)2 
k
Pb + AgNO3 
22
l
Ca + HCl 
7 The following equations are based on double decomposition. Complete and balance the
flowing equations.
a
CuSO4 + NaO  ________ +
___________
b
Cu(OH)2 + ________  CuCl2 + ___________
c
________ + KOH  Fe(OH)2 + ___________
d
KOH + ________  KCl + ___________
e
CaCl2 + NaOH  _______ + __________
f
________ + ________  PbSO4 + __________
g
AgNO3 + HCl  _______ + _________
h
________ + _______  CaSO4 + H2O
i
ZnCl2 + _______  Zn(OH)2 + _________
LINKS:
 http://www.khanacademy.org/science/chemistry/v/balancing-chemical-equations
 http://www.youtube.com/watch?v=Ym1ln3LG46k&feature=relmfu
 http://www.youtube.com/watch?v=Teaexn1luBA&feature=relmfu
 http://www.youtube.com/watch?v=yuStJotow2I&NR=1&feature=fvwp
 https://docs.google.com/present/edit?id=0AcLTInP8Zbs6ZGRqY2dycTlfNzRkdDd3Z
3B0dA

Saturday, 13 September 2014

WORKSHEEET - ACID, BASES, AND SALTS

Section: Exposition
Each question carries 1 mark:
1. F ill in the blanks:

(a) The chemical name of baking soda is _________.

(b) Sodium carbonate decahydrate is the chemical name of ____________

(c) The compound CuSO4.5H2O is called ______________

(d) Hydrated copper sulphate contains five molecules of ________ of crystallization.

(e) The common name of calcium oxy chloride is _________

2. M atch the important chemicals given in column A with the chemical name and formulae given
in column B.
Column A Column B
(a) Plaster of Paris (i) CaSO4.2H2O
(b) Bleaching powder (ii) Na2CO3. 10 H2O
(c) Washing soda (iii)CaSO4. 1/2 H2O
(d) Baking soda (iv) CaOCl2
(e) Gypsum (v) NaHCO3

3. WHO AM I
(a) I am an important constituent of baking powder. If I am not present, the cake will taste
bitter. Identify me and give my molecular formula

(b) I am an important compound of calcium. I am used for sterilizing drinking water and
also used as an oxidising agent in chemical industries. Give my chemical name and
molecular formula.

(c) If I am not present in cement, it will set hard very fast. What is my common name and
molecular formula?

(d) I am a compound of sodium and I am used in glass industry and for softening hard
water. Give my common name and chemical name.

(e) I am a compound of sodium and I am used in fire extinguishers. I am also an important
antacid .What is my common name and chemical name?

(f) I am a chemical substance that gives pink colour in basic medium and remains colourless in acidic medium. What am I?

(g) I am used in hospitals by orthopaedic doctors and I am also used for decoration purpose. Identify and give my molecular formula.

(h) I am evolved when metal carbonate are made to react with dilute acids. Which gas am I?

Each question carries 2 marks:
4. Complete the following table:
S.No Name of hydrated salt Formula Colour

1 Blue vitriol

2 Green vitriol

3. Epsom salt

4. Washing soda

4. Gypsum

5. Plaster of paris

Each question carries 3 marks:

5. While constructing a house, a builder selects marble flooring and marble table tops for the kitchen where vinegar and juices of lemon, tamarind etc. are more often used for cooking. Will you agree to this selection and why?

Each question carries 1 mark:

6. Complete the following reactions:
(a) NaCl +H2O →

(b) Ca(OH)2 + Cl2 →

(c) NaCl + H2O + CO2 + NH3 →

(d) 2 NaHCO3 → heat →

(e) CaSO4.1/2 H2O +11/2 H2O →

Each question carries 2 marks:

7.Write chemical equation for the following industrial preparation, mention two important properties and use of the compound prepared
(a)
(b)
(c)

8. Write the names and chemical formula of the products formed by the:
(a) Action of chlorine on slaked lime
(b) Heating gypsum at 373 K

Each question carries 3 marks:

9. Crystals of copper sulphate are heated in a test tube for some time.
(a) What is the colour of copper sulphate crystals before heating, and after heating?
(a) What is the source of liquid droplets seen on the inner upper side of the test tube during the heating process?

Section: Interpretation & Reasoning

Each question carries 1 mark:

10. A gas is produced when conc. H2SO4 is added to solid sodium chloride taken in a test tube. The gas coming out through the delivery tube is passed over a dry blue litmus paper and then over a moist blue litmus paper. What would you observe? Explain the reason with the help of a chemical equation.
Each question carries 2 marks:

11. A compound ‘X’ of sodium is commonly used in kitchen for making crispy pakoras. It is also used for curing acidity in the stomach. Identify ‘X’. What is its chemical formula? State the reaction which takes place when it is heated during cooking.

12. A substance X, which is an oxide of a metal, is used intensively in the cement industry This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the equation for its chemical reactions with water

13.In one of the industrial processes used for manufacture of sodium hydroxide, a gas ‘X’ is formed as a by-product. The gas ‘X’ reacts with dry slaked lime to give a compound ‘Y’ which is used as a bleaching agent in one chemical industry. Identify X and Y.

Each question carries 3 marks:

14. Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which itself is used for removal of hardness of water and a gas ‘C’ is evolved. The gas ‘C’ when passed through lime water turns it milky. Identify A, B and C.

15. A white powder ‘A’ is a mild non corrosive base and is used in the preparation of cakes. When the powder is heated it gives another powder ‘B’. The powder ‘B’ is recrystallised to get a substance ’C’ which has detergent properties. Identify A, B and C and also write balanced chemical equations for the conversions of ‘A’ to ‘B’.

16. Identify the compound of calcium which is a yellowish white powder and is used for disinfecting drinking water. How is it manufactured? Write the chemical equation for the reaction involved. What happens when it is left exposed to air?

WORKSHEET ON ACID, BASE AND SALT

Section: Exposition
Each question carries 1 mark:

1. State whether the following statements are true or false. Rewrite the false statement
correctly
(a) Neutral solution have pH of 0
(b) Solution of sodium hydrogen carbonate is acidic in nature.
(c) Correct increasing order of the acidic strength is: Water < Acetic acid< Hydrogen
chloride
(d) The colourless gas B is produced when egg shell is treated with a solution A. The
gas B turns lime water milky. A=HCl and B=CO2

2. Fill in the blanks:
(a) An indicator changes its _______ with change of the nature of the solution.
(b) An acid produces ______ ion in aqueous solution.
(c) The properties of ______ are due to the hydrogen ion it produces in aqueous
solution.
(d) A water soluble base produces _____ ions in solutions.
(e) The reaction between an acid and base is called _____ reaction.
(f) The concentration of H+ ion given by HCl is _____ than that given by equal
concentration of CH3COOH.

3. Which oxides are acidic and which oxides are basic?

4. How can you test that metallic oxides are basic while non -metallic oxides are acidic?

5. Name one oxide which is both acidic as well as basic .What are these oxides called?

6. Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn
litmus solution from blue to red and which will turn phenolphthalein from colorless to pink?

7. Ishaan prepared China rose indicator by keeping the petals of the flower in hot water for
some time. He used the coloured solution for testing three solutions A,B and C. Solution A
turns to dark pink, solution B remains light pink and solution C turns to green. Mark the
correct

Solution A Solution B Solution C

Lemon juice Sugar solution Milk of magnesia

lemon juice Orange juice Sugar solution

Orange juice Vinegar Salt solution

8. Ravi Shankar took a small amount of sulphur in deflagrating spoon and heated it over a burner. As soon as it started burning he put it in a gas jar and covered it with a lid. After sulphur stopped burning he added a small amount of water in it and dissolved the gas in water by shaking it. He then tested the solution with red and blue litmus paper. What did he observe?

(a) In the solution the blue litmus paper turned red.
(b) In the solution the red litmus paper turned blue.
(c) There was no change in the colour of litmus paper.
(d) Blue litmus paper turned red and red litmus paper turned blue.

Each question carries 2 marks:

9. Complete the following ionization reactions:
(a) HCl (aq) →
(b) H2SO4 (aq)→
(c) HNO3 (aq) →
(d) NaOH(aq) →

10. Write balanced chemical equations for the following word equations:
(a) Reaction of an acid with metal
Calcium + Hydrochloric Acid → Calcium chloride + Hydrogen
(b) Reaction of a base with metal
Zinc + Sodium Hydroxide → Sodium zincate + Hydrogen
(c) Reaction of an acid with metal carbonate/ metal hydrogen carbonate
Calcium carbonate + Hydrochloric acid → Calcium chloride + Carbon dioxide
+ Water
(d) Reaction of an acid with metallic oxides
Magnesium oxide + Hydrochloric acid → Magnesium Chloride + Water

11.A student dropped few pieces of calcium carbonate in dilute hydrochloric acid, contained in a test tube. The carbon dioxide gas evolved was then passed through lime water(calcium hydroxide)and it turned milky due to the formation of insoluble calcium carbonate. Write the balanced chemical equations for all the changes observed

12. Litmus paper is used as an indicator to check whether a solution is acidic or basic. When red litmus is dipped in a basic solution, it turns blue and when blue litmus paper is dipped in an acidic solution, it turns red. If you were given a strip of blue litmus paper, which pair of substances would help you turn it red?

(a) Soap solution and bleach

(b) Ammonia and egg white

(c) Egg yolk and black coffee

(d) Distilled water and sea water

Each question carries 2 marks:

13. Observe the following activity and answer the questions that follow:

(a) What do you observe in boiling test tube ‘A’
(b) Write the balanced chemical equation for the reaction taking place in test tube ‘ A’
(c) What do you observe when the colourless gas is passed through solution of calcium hydroxide? Also write the relevant equation
(d) What will happen if sodium carbonate is replaced by sodium hydroxide solution in test tube ‘A’?

14. Study the following pH chart and answer the questions that follows:

Each question carries 3 marks

Study the following chart and answer the questions that follows:
(a) Which solution has more hydrogen ion concentration?
(b) The pH values of three acids A,B, C having hydrogen ion concentration are 1x10-5 , 1x10-2 and 1x103 respectively. Arrange these acids in order of increasing acid strength

(c) 1.0 mL of lemon juice was taken in a test tube. Its pH was determined by using a
pH paper. Excess of NaOH solution was then added to the lemon juice and the pH
of the resulting solution was again determined It was observed that the color of the
pH paper changed from _____________ to ___________________ .

(d) The pH of soil A is 7.0 and that of soil B is 4.0.Which of these should be treated
with Ca(OH)2 and why?

Each question carries 3 marks:

Interpretation & Reasoning
Each question carries 1 mark:

18. What will you observe when dilute hydrochloric acid is added to a small amount of copper oxide in a beaker?
19. Aqueous solution of HCl shows acidic character. But the aqueous solution of glucose fails to do so. Why?
Compound ‘X’
+ Zn → ‘A’ +H2(g)
+ HCl → ‘B’ +H2O
+ CH3COOH → ‘C’ +H2O

Each question carries 2 marks:

20. A white solid when dropped in water produces a hissing sound. What may the solid be? Give a chemical reaction for the above. Name the product formed.

21. An element ‘X’ on reaction with a dilute acid evolves a gas that burns with a pop sound, while a compound ‘Y’ on reaction with dilute acid evolves a gas that turns lime water milky. Identify X and Y.
22.
22. What is the basicity of phosphoric acid and hydrochloric acid? What is the role of the acid in our stomach?

Each question carries 3 marks:

23. Taj Mahal is getting spoiled due to acid rain. The gases present in atmosphere are SO2, SO3 and NO2. Which acids will react with Taj Mahal ? Explain with the help of chemical reactions.
24. Name the chemicals used in the Soda acid Fire extinguisher and the gas evolved from it when used? Why is NaHCO3 used in soda-acid fire extinguishers?
Section: Problem Solving
25. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y, Z.

Wednesday, 7 January 2015

REVISION WORK

REVISION WORK

I. ONE MARK QUESTIONS;

1. When a white powder was mixed with acetic acid a colourless gas produced

which turns lime water milky. What is the white powder?

2. What are saturated hydrocarbons?

3. Write the structural formula of any isomer of n-heptane? (C₇H₁₆)

4. Define the term catenation.

II. TWO MARKS QUESTIONS:

1. Give two limitations of Mendeleev’s periodic classification.

2. How does valency vary in a period on going left to right and in going down a group?

3. Give reason: why the atomic radii of elements increases in a group while moving from top to bottom?

4. State Mendeleev’s periodic law. why could no fixed position be given to hydrogen in mendeleev’s periodic table?

5. i. name the property of ethanol which makes it useful in medicines.

ii. name the organic compound used in pickles. Mention its composition.

III. THREE MARKS QUESTIONS:

1. Write molecular, electronic and structural formulae of ethane.

2. A. How does valence electrons vary :

i) In a group ii) in a period

b. why do all elements in a group have same chemical properties?

c . How does tendency to lose electrons vary along a period? Why?

3. A.distinguish between esterification and saponification reactions of organic compound.

b. describe an activity to show the formation of an ester.

4. complete the following reactions:

a. C₂H₅OH + CH₃COOH -----à

b. R-C=C-R + H₂----à

c. CH₃COOC₂H₅ + NaOH ----à

5. An organic acid ‘X’ is a liquid which often freezes during winter time in cold countries, has the molecular formula C₂H₄O₂ . on warming it with ethanol in the presence of few drops of con. H₂SO₄., a compound ‘Y’ with sweet smell is formed.

i. identify ‘X’ and ‘Y’.

ii. write a chemical equation for the reaction involved.

6. i. an element has atomic number 12. Is it metal or non-metal, why?

ii. why do we classify elements?

iii. do isotopes have same or different places in modern periodic table? Give reasons.

IV. FIVE MARKS QUESTIONS:

1. A) what would be electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur?

b) draw electron dot structure of ethane.

2. a. draw all structural isomers of pentane.

b. draw structure of Butanone and bromopentane.

3. give an example of each:

a. a carbon compound containing two double bond.

b. a molecule in which central atom is linked to three other atoms.

c. a compound containing both ionic and covalent bond

d. an organic compound soluble in water

e. a carbon compound burns with a sooty flame.

4. atomic number of few elements are given below:

10, 20, 7, 14

a. Identify these elements

b. Identify group number of these elements

c. Period of the elements

d. Electronic configuration of these elements

e. Determine the valency of these elements

5. a. why does carbon form compounds mainly by covalent bonding?

b. what if 5% solution of KMnO₄ is added drop by drop to warm ethanol taken in a test tube

c. give a chemical test to distinguish ethanol from ethanoic acid.

6. a. name the element with atomic number 12(.ans: Mg)

b. name a metal in making cans and member of group 14. (ans: Tin)

c. a lustrous non metal having 7 valence electrons.( ans; Iodine)

d. highly reactive metal given violet colour to flame. ( ans: K)

e. a gas used in coloured advertising lights having 2 valence electrons (Ne)

7. Identify A to E in the following equations:

a. CH₃CH₂OH -----àA (in presence of KMnO₄and KOH)

b. CH₃CH₂OH + A --à B (in presence of con. H₂SO₄)

c. NaOH + B ---à C + CH₃CH₂OH

d. NaHCO₃ + A ----à C + D + H₂O

e. CH₃CH₂OH + E ---à CH₃CH₂COONa + H₂

ANS: a. ethanoic acid b. ethyl ethonoate c. Sodium ethanoate d. CO₂ e. Na

8.a. complete the following reactions:

a. CH₃CH₂CH₂OH + 2 [O] --à

b. C₂H₅COOH + NaHCO₃ -----à

c. C₃H₇COOC₂H₅ + NaOH ----à

B. Write the names of the compound:

a. CH₃CH₂COCH₃

b. CH₃COOC₂H₅

ANS: a. CH₃CH₂CH₂OH + 2 [O] --à CH₃CH₂COOH + H₂O

b. C₂H₅COOH + NaHCO₃ -----à C₂H₅COONa + CO₂ + H₂O

c. C₃H₇COOC₂H₅ + NaOH ----à C₃H₇COONa + C₂H₅OH

B . a. CH₃CH₂COCH₃- Butan -2-one

b. CH₃COOC₂H₅ - Ethyl Ethanoate

9. an organic compound ‘X’ on heating with con. Sulphuric acid, forms a compound ‘Y’ which on addition of one molecule of hydrogen in the presence of Ni forms a compound ‘Z’. One molecule of compound ‘Z’ on combustion forms two molecules of CO₂ and three molecules of H₂O. Identify ‘X’ , ‘Y’ and ‘Z’ and write the reactions involved.

ANS: since 1 molecule of Z gives 2 molecule of CO₂ and 3 molecules of H₂O on combustion, it means Z has two carbon and its molecular formula is C₂H₆.

The compound Z is obtained by addition of 2 hydrogen to Y . therefore Y is C₂H₄. The compound Y is obtained by heating compound ‘X’ is with con. H₂SO₄., it means X is C₂H₅OH.

Refer NCERT book p.no. 72