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Unit3 Stoichiometry qns

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

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1 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 3. The mass equivalent of one a.m.u. is 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 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 ? 7. Loschmidt number is 8. The number of water molecules in a drop of water measuring 0.05 ml is 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 11. The number of atoms in 1.00 gram of gold (at. Wt. 197) is 12. The weight of one atom of Uranium is 238 amu. Expressed in grams, its weight is 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 ? 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 ? 16. How many g-atoms of hydrogen are present in 8.5 g of NH 3 ? 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 isotope ?
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2 QUEST TUTORIALS Head Office : E-16/289, Sector-8, Rohini, New Delhi, Ph. 65395439
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