A metal nitride ${\mathrm{M}}_3<mspace\; width="1em"></mspace>{\mathrm{N}}_2$ contains 28% of nitrogen. The atomic mass of metal M is:

1. 24

2. 54

3. 9

4. 87.62

1.0 mol of Fe reacts completely with 0.65 mol of O₂ to give a mixture of only FeO and Fe₂O₃. The mole ratio of ferrous oxide to ferric oxide is

(1) 2 : 2

(2) 4 : 3

(3) 1 : 2

(4) 2 : 7

The percentage of copper in a copper(II) salt can be determined by using a thiosulphate titration. 0.305 gm of a copper(II) salt was dissolved in water and added to, an excess of potassium iodide solution liberating iodine according to the following equation 2Cu² (aq) + 4I^– (aq) $\stackrel{}{\rightleftharpoons }$ 2CuI(s) + I₂(aq) The iodine liberated required 24.5cm³ of a 0.100 mole dm^-3 solution of sodium thiosulphate 2S₂O₃^2- (aq) + I₂(aq) $\underset{}{\overset{}{\to }}$ 2I^– (aq) + S₄O₆^2- (aq) the percentage of copper, by mass in the copper(ll) salt is. [Atomic mass of copper = 63.5]

1. 64.2

2. 51.0

3 48.4

4. 25.5

Oxygen contains 90% O¹⁶ and 10% O¹⁸. Its atomic mass is

(1) 17.4

(2) 16.2

(3) 16.5

(4) 17

KClO₃ on heating decomposes to KCl and O₂. The volume of O₂ at STP liberated by 0.1 mole KClO₃ is

1. 4.36 L

2. 3.36 L

3. 2.36 L

4. None of these

At S.T.P. the density of CCl₄ vapour in g/L will be nearest to [CBSE PMT 1988]

(1) 6.84

(2) 3.42

(3) 10.26

(4) 4.57

4.4 g of an unknown gas occupies 2.24 litres of volume at NTP. The gas may be: 

The mass of carbon present in 0.5 mole of K₄[Fe(CN)₆] is:

1. 1.8 g

2. 18 g

3.  3.6 g

4.  36 g

The number of moles of oxygen in one litre of air containing 21% oxygen by volume under standard conditions is [CBSE PMT 1995]

(1) 0.186 mole

(2) 0.21 mole

(3) 0.0093 mole

(4) 2.10 mole

An organic compound containing C, H, and N gave the following on analysis: C = 40%, H = 13.3% and N = 46.67%. Its empirical formula would be:

1. CHN
2. C₂H₂N
3. CH₄N
4. C₂H₇N