A mixture of methane and ethene in the molar ratio of x : y has a mean molar mass of 20. What would be the mean molar mass. if the gases are mixed in the molar ratio of y : x?

(1) 22                               

(2) 24

(3) 20.8                           

(4) 19

Which of the following contains the greatest number of nitrogen atoms ?

1. 500 ml of 2.0 $\mathrm{M} {\mathrm{NH}}_3$

2. One mole of ${\mathrm{NH}}_4\mathrm{Cl}$

3. $6.02 \times {10}^{23}$ molecules of ${\mathrm{NO}}_2$ gas

4. 22.4 litres of ${\mathrm{N}}_2$ gas at 0ºC and 1 atm.

Calculate number of electrons present in 9.5 g of ${\mathrm{PO}}_4^{3-}$:

1.  $6$

2.  $5 {\mathrm{N}}_{\mathrm{A}}$

3.  $0.1 {\mathrm{N}}_{\mathrm{A}}$

4.  $4.7 {\mathrm{N}}_{\mathrm{A}}$

The total no. of neutrons present in 54 mL ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$ are:

1.  $3 {\mathrm{N}}_{\mathrm{A}}$

2.  $30 {\mathrm{N}}_{\mathrm{A}}$

3.  $24 {\mathrm{N}}_{\mathrm{A}}$

4.  none of these

The volume of a drop of water is 0.0018 mL then the number of water molecules present in two drop of water at room temperature is:

1.  $12.046\times {10}^{19}$

2.  $1.084\times {10}^{18}$

3.  $4.84\times {10}^{17}$

4.  $6.023\times {10}^{23}$

Which of the following combinations illustrates the law of reciprocal proportions?

1.  ${\mathrm{N}}_2{\mathrm{O}}_3, {\mathrm{N}}_2{\mathrm{O}}_4, {\mathrm{N}}_2{\mathrm{O}}_5$

2.  $\mathrm{NaCl}, \mathrm{NaBr}, \mathrm{Nal}$

3.  ${\mathrm{CS}}_2, {\mathrm{CO}}_2, {\mathrm{SO}}_2$

4.  ${\mathrm{PH}}_3, {\mathrm{P}}_2{\mathrm{O}}_3, {\mathrm{P}}_2{\mathrm{O}}_5$

Carbon and oxygen combine to form two oxides, carbon monoxide and carbon dioxide in which the ratio of the weights of carbon and oxygen is respectively      12 : 16 and 12 : 32. These figures illustrate the:

1.  Law of multiple proportions

2.  Law of reciprocal proportions

3.  Law of conservation of mass

4.  Law of constant proportions

The formula of an acid is ${\mathrm{HXO}}_2.$ The mass of 0.0242 moles of the acid is 1.657 g.
The atomic weight of X is:

A 6.85 g sample of the hydrates $\mathrm{Sr}{\left(\mathrm{OH}\right)}_2.{\mathrm{xH}}_2\mathrm{O}$ is dried in an oven to give 3.13 g of anhydrous $\mathrm{Sr}{\left(\mathrm{OH}\right)}_2$. The value of x is - 

(Atomic weights : Sr=87.60, O=16.0, H=1.0)

1.  8

2.  12

3.  10

4.  6

The sulphate of the metal M contains 9.87% of M. This sulphate is isomorphous with ${\mathrm{ZnSO}}_4.7{\mathrm{H}}_2\mathrm{O}$. The atomic weight of M is:

1.  40.3

2.  36.3

3.  24.3

4.  11.3