Page 157 - Chemistry ICSE Class X

Mole Concept and Stoichiometry 143
Q 8. O is evolved by heating KClO using MnO as a catalyst [ICSE 2013]
3
2
2
MnO
2KClO o 2KCl + 3O 2
2
3
(i) Calculate the mass of KClO required to produce 6.72 litre of O at STP.
3
2
[Atomic masses of K = 39, Cl = 35.5, O = 16].
(ii) Calculate the number of moles of oxygen present in the above volume and also the number of molecules.
(iii) Calculate the volume occupied by 0.01 mole of CO at STP.
2
Q 9. Give one word or phrase for the ratio of the mass of a certain volume of gas to the mass of an equal volume of
hydrogen under the same conditions of temperature and pressure. [ICSE 2014]
Q 10. (i) State Avogadro’s Law. [ICSE 2014]
(ii) A cylinder contains 68 g of ammonia gas at STP.
(1) What is the volume occupied by this gas?
(2) How many moles of ammonia are present in the cylinder?
(3) How many molecules of ammonia are present in the cylinder? [N-14, H-1]
Q 11. Oxygen oxidises ethyne to carbon dioxide and water as shown by the equation: [ICSE 2014]
2C H + 5O o 4CO + 2H O
2
2
2
2
2
3
What volume of ethyne gas at STP is required to produce 8.4 dm of carbon dioxide at STP?
[H = 1, C = 12, O = 16]
Q 12. Choose the most appropriate answer for the following: [ICSE 2015]
(i) Which of the following would weigh the least?
(A) 2 gram atoms of nitrogen
(B) 1 mole of silver
(C) 22.4 litres of oxygen gas at 1 atmospheric pressure and 273 K
23
(D) 6.02 × 10 atoms of carbon
(Atomic masses: Ag = 108, N = 14, O = 16, C = 12)
Q 13. Complete the following calculations. Show working for complete credit: [ICSE 2015]
(i) Calculate the mass of calcium that will contain the same number of atoms as are present in
3.2 g of Sulphur. (Atomic masses: S = 32, Ca = 40)

(ii) If 6 litres of hydrogen and 4 litres of chlorine are mixed and exploded and if water is added to the gases
HQTOGF ſPF VJG XQNWOG QH VJG TGUKFWCN ICU
KKK +H VJG GORKTKECN HQTOWNC QH C EQORQWPF KU %* CPF KV JCU C XCRQWT FGPUKV[ QH ſPF VJG OQNGEWNCT HQTOWNC
of the compound.
Q 14. State one relevant observation for the following: [ICSE 2015]
(i) At the anode when aqueous copper sulphate solution is electrolysed using copper electrodes.
Q 15. Consider the following reaction and based on the reaction answer the questions that follow: [ICSE 2015]
heat
(NH ) Cr O o N (g) + 4H O(g) + Cr O 3
7
2
2
2
4 2
2
Calculate:
(i) the quantity in moles of (NH ) Cr O if 63 g of (NH ) Cr O is heated.
2
4 2
7
4 2
7
2
(ii) the quantity in moles of nitrogen formed.
3
(iii) the volume in litres or dm of N evolved at STP.
2
(iv) the mass in grams of Cr O formed at the same time.
3
2
(Atomic masses: H = 1, Cr = 52, N=14)