Chemical Combination

1. How many moles of limestone will be required to produce 5.6g of CaO? (a) 0.21mol (b) 1.12mol (c) 0.10mol (d) 0.56mol
Right Choice: Option C

2. What is the percentage by mass of oxygen in Al2(SO4)3.2H2O? (a) 14.29% (b) 25.36% (c) 50.79% (d) 59.25%
Right Choice: Option D

3. What is the molar mass of a substance, if 0.4mole of the substance 9a) 6.3g (b) 40.0g 9c0 62.5g (d) 2.5g
Right Choice: Option C

4. An element X forms the following compounds with chloride: XCl4,XCl3,XCl2. This illustrates the (a) law of multiple proportion (b) law of simple proportion (c) law of conservation of mass (d) law of definite proportion
Right Choice: Option A

5. 50cm3 of hydrogen are sparked with 20cm3 of oxygen at 100Oc and 1 atmosphere. The total volume of the residual gases is 9a0 50cm3 (b) 70cm3 (c) 40cm3 (d) 30cm3
Right Choice: Option B

6. The empirical formula of an Oxide of Nitrogen containing 30.4 percent of nitrogen is (a) N2O2 (b) NO (c) NO2(d) HN2O (N= 14.0, O = 16.0)
Right Choice: Option A

7. Equal volume of CO2, and CO at STP have the same (a) mass (b) density (d) rate of diffusion (d) number of molecules
Right Choice: Option C

8. Which of the following reactions is correct as written? (a) FeCl2 + 3NH4OH  Fe(OH) + 3NH4Cl
(b) Pb2O3 + 4HCl  PbCl2 +2H2O (c) PbNO3 + H2S  PbS +2HNO3 (d) NaOH + H2SO4  NaHSO4 + H2O
Right Choice: Option C

9. The number of atoms in one mole of a substance is equal to (a) the atomic number (b) the Avogadro number (c) the gas constant (d) the number of neutrons
Right Choice: Option D

10. In an experiment 5.0g of a metal gave 10.59g of its chloride. In another experiment, 1.50g of the same metal combined with 1.68g of chloride. he above data illustrates (a) law of conservation of mass (b) law of definite proportion (c) law of multiple proportion (d) Gay Lussac’s law
Right Choice: Option D

EXERCISE

11. 0.07g of a hydride of carbon occupies 56.0cm3 at S.T.P when vapourized and contains 14.29% by mass of hydrogen. The formula of the hydrocarbon is (C=12, H= 1) (a) CH4 (b) C2H2 (c) C2H4 (d) C2H6

12. 60cm3 of hydrogen are sparked with 20cm3 of oxygen at 100cm and 1 atmosphere. The total volume of the residual gases is (a) 60cm3 (b) 10cm3 (c) 40cm3 (d) 30cm3

13. The balanced equation for the reaction of tetraoxosulphate (VI) acid with aluminum hydroxide to give water and aluminum tetraoxosulphate (VI) is (a) H2SO4 + Al(OH)2  2H2O + AlSO4 (b) HSO4 AlOH  H2O + AlSO4 (c) 3H2SO4 + 2AlH3  6H2O + Al(SO4)3 (d) 3H2SO4 + 2Al(OH)3  6H2O + Al(SO4)3

14. In two separate experiment, 0.36g and 0.71g of chloride combined with a metal X to give Y and Z contain 0.20g and 0.40g of X respectively. The data above represents the law of (a) multiple proportion (b) conservation of mass (c) constant proportion (d) reciprocal

15. How many mole of oxygen molecule would be produced from the decomposition of 2.5moles of potassium trioxochlorate (V)? (a0 2.50 (b) 3.50 (c) 3.75 (d) 7.50

16. What is the molar mass of a substance, if 0.4 mole of the substance has a mass of 25.0g? (a) 6.3g (b) 40.0g (c) 62.5g (d) 2.5g

17. Which of the following gases contains the least number of atoms at S.T.P 9a0 4 moles of Chlorine (b) 3 moles of Ozone (c) 1moles of butane (d) 7 moles of Argon

18. The formula of CH2O for ethanoic acid is regarded as its (a) general formula (b) structural formula (c) molecular formula (d) empirical formula

19. What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen? (a) 36.0g (b) 8.0g 9c) 72.0g (d) 16.0g

20. How many moles of HCl will be required to react with potassium heptaoxodicromate

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