Page 158 - Chemistry ICSE Class X

144 ICSE Chemistry – 10
Q 16. Choose the correct answer from the options given below: [ICSE 2016]
(i) The ratio between the number of molecules in 2 g of hydrogen and 32 g of oxygen is:
(A) 1 : 2 (B) 1 : 0.01
(C) 1 : 1 (D) 0.01 : 1 (Given that H = 1, O = 16)
Q 17. (i) A gas of mass 32 g has a volume of 20 litres at STP. Calculate gram molecular weight of the gas. [ICSE 2016]
KK *QY OWEJ ECNEKWO QZKFG KU HQTOGF YJGP I QH ECNEKWO PKVTCVG KU JGCVGF! #NUQ ſPF VJG XQNWOG QH PKVTQIGP
dioxide evolved :
2Ca(NO ) o 2CaO + 4NO + O 2
2
3 2
(Ca = 40, N = 14, O =16)
24
Q 18. (a) A gas cylinder contains 12 × 10 molecules of oxygen gas. [ICSE 2016]
23
If Avogadro’s number is 6 × 10 ; Calculate:
(i) the mass of oxygen present in the cylinder.
(ii) the volume of oxygen at STP present in the cylinder. (O = 16)
D # ICUGQWU J[FTQECTDQP EQPVCKPU QH ECTDQP )KXGP VJCV KVU XCRQWT FGPUKV[ KU ſPF KVU OQNGEWNCT
formula. (C = 12, H = 1)
3
(c) The equation 4NH + 5O o 4NO + 6H O, represents the catalytic oxidation of ammonia. If 100 cm of
2
3
2
ammonia is used, calculate the volume of oxygen required to oxidise the ammonia completely.
Q 19. (a) (i) Propane burns in air according to the following equation: [ICSE 2017]
C H + 5O o 3CO + 4H O.
8
3
2
2
2
3
What volume of propane is consumed on using 1000 cm of air, considering only 20% of air contains
oxygen?
(ii) The mass of 11.2 L of a certain gas at STP is 24 g. Find the gram molecular mass of the gas.
(b) A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure:
(i) Find the number of moles of hydrogen present.
(ii) What weight of CO can the cylinder hold under similar conditions of temperature and pressure:
2
(H = 1, C = 12, O = 16)
(iii) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO molecules in
2
the cylinder under the same conditions of temperature and pressure.
(iv) State the law that helped you to arrive at the above result.
Q 20. (i) Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23). [ICSE 2017]
(ii) Calculate the percentage of water of crystallization CuSO .5H O (H = 1, O = 16, S = 32, Cu = 64).
4
2
(iii) A compound of X and Y has the empirical formula XY . Its vapour density is equal to its empirical formula
2
weight. Determine its molecular formula.
Q 21. The percentage composition of a gas is: Nitrogen 82.35%, Hydrogen 17.64%. Find the empirical formula of the
gas. [N = 14, H = 1] [ICSE 2018]
Q 22. Aluminum carbide reacts with water according to the following equation: [ICSE 2018]
Al C + 12H O o 4Al(OH) + 3CH 4
3
2
3
4
(i) What mass of aluminum hydroxide is formed from 12 g of aluminum carbide?
(ii) What volume of methane at STP is obtained from 12 g of aluminum carbide?
[Relative molecular weight of Al C = 144; Al(OH) = 78]
3
3
4
Q 23. (i) If 150 cc of gas A contains X molecules, how many molecules of gas B will be present in 75 cc of B?
The gases A and B are under the same conditions of temperature and pressure.
(ii) Name the law on which the above problem is based. [ICSE 2018]
Q 24. Ethane burns in oxygen to form CO and H O according to the equation:
2
2
2C H + 7O o 4CO + 6H O
2
6
2
2
2
If 1250 cc of oxygen is burnt with 300 cc of ethane,
Calculate:
(i) the volume of CO formed. (ii) the volume of unused O . [ICSE 2018]
2
2