Practice Paper Chemistry

1)Identify ‘x’, ‘y’ and ‘z’ in the following reaction :

(a) x = gas; y = reaction condition; z = gas

(b) x = solid; y = liquid; z = gas
(c) x = number of moles of KClO3; y = reaction condition; z = number of molecules of oxygen
(d) x = physical state of KClO3 and KCl;
y = reaction condition, z = physical state of O2.

2)Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen
gases liberated during electrolysis of water is:
(a) 1 : 1
(b) 2:1
(c) 4:1
(d) 1:2

3) Calcium oxide reacts vigorously with water to produce slaked lime.

CaO(s) + H2O(l) → Ca(OH)2(aq)
This reaction can be classified as
(A) Combination reaction
(B) Exothermic reaction
(C) Endothermic reaction
(D) Oxidation reaction
Which of the following is a correct option? (2020)
(a) (A) and (C)
(b) (C) and (D)
(c) (A), (C) and (D)
(d) (A) and (B)

4) A compound ‘A’ is used in the manufacture of cement. When dissolved in water, it evolves
a large amount of heat and forms compound ‘B’.
(i) Identify A and B.
(ii) Write chemical equation for the reaction of A with water.
(iii) List two types of reaction in which this reaction may be classified.

5) Mention with reason the colour changes observe when:

(i) silver chloride is exposed to sunlight.
(ii) copper powder is strongly heated in the presence of oxygen.
(iii) a piece of zinc is dropped in copper sulphate solution.

6) Identify the type of reactions taking place in each of the following cases and write the
balanced chemical equation for the reactions.
(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver.
(b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide

7) Which of the following is the correct arrange-ment of the given metals in ascending order
of their reactivity?
 Zinc, Iron, Magnesium, Sodium
(a) Zinc > Iron > Magnesium > Sodium
(b) Sodium > Magnesium > Iron > Zinc
(c) Sodium > Zinc > Magnesium > Iron
(d) Sodium > Magnesium > Zinc > Iron

8) Decomposition reactions require energy either in the form of heat or light or electricity for
breaking down the reactants. Write one equation each for decomposition reactions where
energy is supplied in the form of heat, light and electricity.

9) What is observed when carbon dioxide gas is passed through lime water
(i) for a short duration?
(ii) for a long duration? Also write the chemical equations for the reactions involved.

10) ’What are amphoteric oxides ? . Write chemical equations that show aluminium oxide reacts with
acid as well as base.

11) Write the names of the product formed when zinc reacts with NaOH. Also write the balanced
chemical equation for the reaction involved. Write a test to confirm the presence of the gas evolved
during this reaction.

12) On diluting an acid, it is advised to add acid to water and not water to acid. Explain why it is so
advised?
13) (i) Draw a labelled diagram to show the preparation of hydrogen chloride gas in laboratory.
(ii) Test the gas evolved first with dry and then with wet litmus paper. In which of the two cases, does
the litmus paper show change in colour?
(iii) State the reason of exhibiting acidic character by dry HCl gas/HCl solution.

14) Complete and balance the following chemical equations :

(i) NaOH(aq) + Zn(s) →
(ii) CaCO3(s) + H2O(l) + CO2(g) →
(iii) HCl(aq) + H2O(l) →

15) Out of HCl and CH3COOH, which one is a weak acid and why? Explain with the help of an
example.

16) Explain how an antacid works.

17) List the important products of the Chlor-alkali process. Write one important use of each.

18) To. a solution of sodium hydroxide in a test tube, two drops of phenolphthalein are added.
(i) State the colour change observed.
(ii) If dil HCl is added dropwise to the solution, what will be the colour change?
(iii) On adding few drops of NaOH solution to the above mixture the colour of the solution
reappears. Why?

19) Give reasons for the following:

(i) Only one half of water molecule is shown in the formula of plaster of Paris.
(ii) Sodium hydrogen carbonate is used as an antacid.
(iii) On strong heating, blue coloured copper sulphate crystals turn white
20) Chemical formula of washing soda is -- .

21) Write one point of difference between each of the following:

(i) A hydrated salt and an anhydrous salt.
(ii) Washing soda and soda ash.
(iii) Baking soda and baking powder.

22) Name a metal which:

(a) is the best conductor of heat.
(b) has a very low melting point.
(c) does not react with oxygen even at high temperature.
(d) is most ductile.

23) ive reason for the following:

(i) Hydrogen gas is not evolved when most of the metals react with nitric acid.
(ii) Zinc oxide is considered as an amphoteric oxide.
(iii) Metals conduct electricity.

24) (a) Why does calcium start floating when it reacts with water? Write the balanced chemical
equation of the reaction.
(b) Name two metals which do not react with water.

25) A metal ‘X’ combines with a non-metal ‘Y’ by the transfer of electrons to form a compound Z.
(i) State the type of bond in compound Z.
(ii) What can you say about the melting point and boiling point of compound Z?
(iii) Will this compound dissolve in kerosene or petrol?
(iv) Will this compound be a good conductor of electricity?

26) Zinc is a metal found in the middle of the activity series of metals. In nature, it is found as a
carbonate ore, ZnCO3. Mention the steps carried out for its extraction from the ore. Support with
equations.

28) (a) List in tabular form three chemical properties on the basis of which we can differentiate
between a metal and a non¬metal.
(b) Give reasons for the following :
(i) Most metals conduct electricity well.
(ii) The reaction of iron (III) oxide [Fe2O3] with heated aluminium is used to join cracked machine
parts.
29) (a) Copper produced by heating the ore in air is not very pure. Describe the method used for
refining impure copper. Draw labelled diagram of the process.
(b) Write chemical equations for the reactions taking place when :
(i) zinc sulphide is heated in air.
(ii) zinc carbonate is calcined.

30) (a) Name the following :

(i) Metal that can be cut by knife
(ii) Lustrous non-metal
(iii) Metal that exists in liquid state at room temperature
(iv) Most malleable and ductile metal
(v) Metal that is best conductor of electricity
(vi) Non-metal that can exist in different forms
(b) How are alloys better than metals? Give composition of solder and amalgum’

31) Aman took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting
a test tube over it, as shown in the figure.
(a) What will be the action of gas on
(i) dry litmus paper ?
(ii) moist litmus paper ?
(b) Write a balanced chemical equation for the reaction taking place.

33) Give reason for the following :

(a) Ionic compounds have higher melting point and higher boiling point.
(b) Sodium is kept immersed in kerosene.
(c) Reaction of calcium with water is less violent.
(d) Silver articles become black after some time when exposed to air.
(e) Prior to reduction the metal sulphides and carbonates must be converted into metal oxides for
extracting metals.

34) On dropping a small piece of sodium in a test tube containing carbon compound ‘X’ with
molecular formula C2H6O, a brisk effervescence is observed and a gas ‘Y’ is produced. On bringing a
burning splinter at the mouth of the test tube the gas evolved burns with a pop sound. Identify ‘X’
and ‘Y’. Also write the chemical equation for the reaction. Write the name and structure of the
product formed, when you heat ‘X’ with excess cone, sulphuric acid.

35) Covalent compounds have low melting and boiling point. Why

36) Give reasons for the following:

(i) Element carbon forms compounds mainly by covalent bonding.
(ii) Diamond has high melting point.
(iii) Graphite is a good conductor of electricity.

37) Name the following compounds :

(a) CH3 – CH2 – OH

Answer:
(a) CH3 – CH2 – OH : Ethanol

38) A carboxylic acid (molecular formula, C2H4O2) reacts with an alcohol in the presence of an acid
catalyst to form a compound ‘X’. The alcohol on oxidation with alkaline KMnO4 followed by
acidification gives the same carboxylic acid C2H4O2. Write the name and structure of (i) carboxylic
acid, (ii) alcohol and (iii) the compound ‘X’

39) Name the process by which unsaturated fats are changed to saturated fats; Explain with
equation”

40) 37Nisha observed that the bottoms of cooking utensils were turning black in colour while the
flame of her stove was yellow in colour. Her daughter suggested cleaning the air holes of the
 stove to get a clean, blue flame. She also told her mother that this would prevent the fuel from
getting wasted.

1. Identify the reasons behind the sooty flame arising from the stove.

2. Can you distinguish between saturated and unsaturated compounds by burning them?
Justify your answer.

41) Write the next homologue of each of the following:

(i) C2H4
(ii) C4H6

42) Name the following compounds :

(a) CH3 – CH2 – OH

43) Write the name and structure of an alcohol with four carbon atoms in its molecule.

44) Write the name and structure of an aldehyde with four carbon atoms in its molecule.

45) What is homologous series of carbon compounds? Explain with example;

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