Unit3 Stoichiometry qns

Unit3 Stoichiometry qns - 1 UNIT 3 GENERAL CHEMISTRY :...

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QUEST TUTORIALS Head Office : E-16/289, Sector-8, Rohini, New Delhi, Ph. 65395439 UNIT 3 GENERAL CHEMISTRY : STOICHIOMETRY 1. Avogadro’s number equals the number of (a) molecules per gram (b) atoms per gram-equivalent (c) atoms per gram-atom (d) electrons per coulomb 2. The number of oxygen atoms in 72 g of water are (a) N (b) 2N (c) 4N (d) 8N 3. The mass equivalent of one a.m.u. is (a) 1/12 th the mass of one C-12 atom (b) 1.67 × 10 –24 g (c) 1.67 × 10 –31 kg (d) all the above 4. The density of hydrogen at S.T.P. is 0.09 g/litre. The number of H 2 molecules in a small bubble of the gas, whose volume at S.T.P. is 0.63 ml is (a) 8.1 × 10 17 (b) 1.6 × 10 29 (c) 1.1 × 10 27 (d) none of these 5. How many moles of ferric alum, (NH 4 ) 2 SO 4 . Fe 2 (SO 4 ) 3 . 24 H 2 O, can be made from a sample of iron containing (a) 3.0 × 10 –4 (b) 5.0 × 10 –4 (c) 1.5 × 10 20 (d) none of these 6. Which of the following masses of 12 C contain 1 mole of electrons ? (a) 12 g (b) 6 g (c) 2 g (d) 1 g 7. Loschmidt number is (a) 6.0 × 10 23 (b) 2.7 × 10 19 (c) 3.0 × 10 23 (d) 2.24 × 10 27 8. The number of water molecules in a drop of water measuring 0.05 ml is (a) 2.0 × 10 21 (b) 6.0 × 10 23 (c) 55.4 (d) none of these 9. Which of the following contains the largest number of molecules ? (a) 1.0 g CH 4 (b) 1.0 g H 2 O (c) 1.0 g HNO 3 (d) 1.0 g N 2 O 4 10. The electrolysis of 72 g of water will yield (a) 8.0 g of O 2 (b) 9 g of O 2 (c) 36 g of O 2 (d) 64 g of O 2 11. The number of atoms in 1.00 gram of gold (at. Wt. 197) is (a) 1.19 × 10 26 (b) 3.05 × 10 21 (c) 3.27 × 10 24 (d) none of these 12. The weight of one atom of Uranium is 238 amu. Expressed in grams, its weight is (a) 1.43 × 10 26 (b) 3.94 × 10 –22 (c) 6.99 × 10 –27 (d) none of these 13. The atomic weight of hydrogen is 1.008 therefore 1008 grams of hydrogen contain (a) 6.02 × 10 26 atoms (b) 5.97 × 10 6 atoms (c) 6.02 × 10 20 atoms (d) none of these 14. A solution of H 2 SO 4 contains 3.60 g of H 2 SO 4 in 1000 g of water. What fraction of the total number of molecules is H 2 SO 4 ? (a) 0.00066 (b) 0.00033 (c) 0.00132 (d) none of these 15. Suppose that x and y are two elements that form the compounds, Y 2 X 3 and Y 2 X. If 0.05 moles of Y 2 X 3 weigh 9.0 g, and 0.10 moles of Y 2 X weigh 10 g, what are the atomic weights of x and y ? (a) 40, 30 (b) 80, 60 (c) 18, 27 (d) 27, 18 16. How many g-atoms of hydrogen are present in 8.5 g of NH 3 ? (a) 1.5 (b) 0.50 (c) 9.03 × 10 23 (d) 1.2 17. How many sulphur atoms would weigh 40.0 g ? (a) 7.53 × 10 20 (b) 7.53 × 10 21 (c) 7.53 × 10 22 (d) 7.53 × 10 23 18. Naturally occuring boron consists of 10 B (10.013 amu) and 11 B (11.009 amu). The atomic weight of Boron is 10.811 amu. What is the relative abundance of lighter
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This note was uploaded on 10/05/2011 for the course CHEM 1201 taught by Professor Darcy during the Spring '11 term at St. Mary NE.

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Unit3 Stoichiometry qns - 1 UNIT 3 GENERAL CHEMISTRY :...

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