ACCLIVITY

WEEKLY PRACTICE PAPER 2

CLASS : XI
SUBJECT : CHEMISTRY

Basic Concept of Chemistry

1. Volume of CO2 obtained at STP by the complete decomposition of 9.85 g Na2CO3 is :

(1) 2.24 litre
(2) Zero
(3) 0.85 litre
(4) 0.56 litre

2. One litre of CO2 is passed through red hot coke. The volume becomes 1.4 litres at the same temperature and
pressure. The composition of products is :
(1) 0.8 litre of CO2 and 0.6 litre of CO
(2) 0.7 litre of CO2 and 0.7 litre of CO
(3) 0.6 litre of CO2 and 0.8 litre of CO
(4) 0.4 litre of CO2 and 1.0 litre of CO

3. An organic compound containing C and H gave the following analysis C = 40%, H = 6.7%. Its empirical
formula would be -
(1) CH4
(2) CH2O
(3) C2H4O2
(4) C2H4

4. How many litres of oxygen at STP is required to burn 60 g C2H6 ?

(1) 22.4 L
(2) 11.2 L
(3) 22.4 × 7 L
(4) 8.5 L

5. For the formation of 3.65 g of HCl gas, what volume of hydrogen gas and chlorine gas are required at NTP
conditions ?
(1) 1 L, 1 L
(2) 1.12 L, 2.24 L
(3) 3.65 L, 1.83 L
(4) 1.12 L, 1.12 L
6. The crystalline salt Na2SO4.xH2O on heating loses 55.9% of its mass ad becomes anhydrous. The formula of
crystalline salt is -
(1) Na2SO4.5H2O
(2) Na2SO4.7H2O
(3) Na2SO4.2H2O
(4) Na2SO4.10H2O

7. A certain amount of a metal whose equivalent mass is 28 displaces 0.7 L of H2 at S.T.P. from an acid, the
mass of the element is -
(1) 1.75 g
(2) 0.875 g
(3) 3.50 g
(4) 7.00 g

8. When 100 ml of M/10 H2SO4 is mixed with 500 ml of M 10 NaOH then the nature of the resulting solution
and normality of excess of reactant left is -

9. Mole fraction of solvent in aqueous solution of NaOH having molality of 3 is -

(1) 0.3
(2) 0.05
(3) 0.7
(4) 0.95

10. Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 gmL–1. Volume of
acid required to make one litre of 0.1 M H2SO4 solution is -
(1) 16.65 mL
(2) 22.20 mL
(3) 5.55 mL
(4) 11.10 mL

11. Ammonia gas is passed into water, yielding a solution of density 0.93 g/cm3 and containing 18.6% NH3 by
weight. The mass of NH3 per cc of the solution is -
(1) 0.17 g/cm3
(2) 0.34 g/cm3
(3) 0.51 g/cm3
(4) 0.68 g/cm3

12. 6.025 × 1020 molecules of acetic acid are present in 500 ml of its solution. The concentration of the solution
is :
(1) 0.002 M
(2) 10.2 M
(3) 0.012 M
(4) 0.001 M
13. Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2
weighs 10 g and 0.05 mole of X3Y2 weighs 9 g, the atomic weights of X and Y are :
(1) 40, 30
(2) 60, 40
(3) 20, 30
(4) 30, 20

14. What is the mass of the precipitate formed when 50 mL of 16.9% solution of AgNO3 is mixed with 50 mL
of 5.8% NaCl solution ? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)
(1) 7 g
(2) 14 g
(3) 28 g
(4) 3.5 g

15. If Avogadro number NA, is changed from 6.022 × 1023 mol–1 to 6.022 × 1020 mol–1, this would change -
(1) The ratio of chemical species to each other in a balanced equation
(2) The ratio of elements to each other in a compound
(3) The definition of mass in units of grams
(4) The mass of one mole of carbon

16. 20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g
magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample ? (At. wt. : Mg
= 24)
(1) 60
(2) 84
(3) 75
(4) 96

17. A mixture of gases contains H2 and O2 gases in the ratio of 1 : 4 (w/w). What is the molar ratio of the two
gases in the mixture ?
(1) 2 : 1
(2) 1 : 4
(3) 4 : 1
(4) 16 : 1

18. 1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and how
much ? (At. wt. Mg = 24; O = 16)
(1) Mg, 0.16 g
(2) O2, 0.16 g
(3) Mg, 0.44 g
(4) O2, 0.28 g
19. When 22.4 litres of H2(g) is mixed with 11.2 litres of Cl2(g), each at STP, the moles of HCl(g) formed is
equal to :
(1) 1 mol of HCl(g)
(2) 2 mol of HCl(g)
(3) 0.5 mol of HCl(g)
(4) 1.5 mol of HCl(g)

20. 6.02 × 1020 molecules of urea are present in 100 mL of its solution. The concentration of solution is :
(1) 0.01 M
(2) 0.001 M
(3) 0.1 M
(4) 0.02 M

21. How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2 M HNO3 ? The
concentrated acid is 70% HNO3.
(1) 90.0 g conc. HNO3
(2) 70.0 g conc. HNO3
(3) 54.0 g conc. HNO3
(4) 45.0 g conc. HNO3

22. Mole fraction of the solute in a 1.00 molal aqueous solution is :

(1) 1.7700
(2) 0.1770
(3) 0.0177
(4) 0.0344

23. Which one of the following has the maximum number of molecules ?
(1) 8 g H2
(2) 64 g SO2
(3) 44 g CO2
(4) 48 g O3

24. The number of atoms in 0.1 mol of a triatomic gas is (NA = 6.02 × 1023 mol–1) :
(1) 6.026 × 1022
(2) 1.806 × 1023
(3) 3.600 × 1023
(4) 1.800 × 1022

25. 3 g of sodium carbonate, Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium
carbonate dissociates completely, molar concentration of sodium ion, Na+ and carbonate ions, CO32- are
respectively (Molar mass of Na2CO3 = 106 g mol–1) :
(1) 0.955 M and 1.910 M
(2) 1.910 M and 0.955 M
(3) 1.90 M and 1.910 M
(4) 0.477 M and 0.477 M
26. 10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. The amount of water
produced in this reaction will be -
(1) 3 mol
(2) 4 mol
(3) 1 mol
(4) 2 mol

27. How many moles of lead (II) chloride will be formed from a reaction between 6.5g of PbO and 3.2 g of
HCl ?
(1) 0.029
(2) 0.044
(3) 0.333
(4) 0.011

28. The volume occupied by one molecule of water (density = 1 g cm–3) is -

(1) 5.5 × 10–23 cm3
(2) 9.0 × 10–23 cm3
(3) 6.023 × 10–23 cm3
(4) 3.0 × 10–23 cm3

29. What volume of oxygen gas (O2) measured at 0°C and 1 atm, is needed to burn completely 1 L of propane
gas (C3H8) measured under the same conditions ?
(1) 10 L
(2) 7 L
(3) 6 L
(4) 5 L

30. An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H,
9.67%. The empirical formula of the compound would be -
(1) CH4O
(2) CH3O
(3) CH2O
(4) CHO