2.0 g sample containing ${\mathrm{Na}}_2{\mathrm{CO}}_3$and ${\mathrm{NaHCO}}_3$ loses 0.248 g when heated to 300$°$C, the temperature at which ${\mathrm{NaHCO}}_3$ decomposes to ${\mathrm{Na}}_2{\mathrm{CO}}_3$, ${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$. What is the % of ${\mathrm{Na}}_2{\mathrm{CO}}_3$ in mixture?

1.66.5

2.50.6

3.60.5

4.6.65

A sample of ${\mathrm{CaCO}}_3$ and ${\mathrm{MgCO}}_3$ weighed 2.21 g is ignited to constant mass of 1.152 g. Calculate the volume of ${\mathrm{CO}}_2$ evolved at $0°\mathrm{C}$ and 76 cm of pressure.

1.640 ml

2.540 ml

3.500 ml

4.600 ml

The average molar mass of the mixture of ${\mathrm{CH}}_4$ $$and ${\mathrm{C}}_2{\mathrm{H}}_4$ present in the mole ratio of a:b is
20 g mol^-1. When the mole ratio is reversed, the molar mass of the mixture will be:

Vapour density of a volatile substance is 4 $\left({\mathrm{CH}}_4=1\right)$. Its molar mass would be:

1.  8

2.  2

3.  64

4.  128

The haemoglobin from the red blood corpuscles contains approximately 0.33%  iron
by mass. The molar mass of haemoglobin is 67,200. The number of iron atoms in each molecule of haemoglobin is :
(atomic mass of iron=56):

The vapour density of a volatile chloride of a metal is 95 and the specific heat of the metal is 0.13 cal/g. The equivalent mass of the metal will be:

1.  6 g
2. 12 g
3.  18 g
4.  24 g

Which mixture is lighter than humid air?

1.  ${\mathrm{N}}_2+{\mathrm{O}}_2+{\mathrm{SO}}_2$

2.  ${\mathrm{N}}_2+{\mathrm{O}}_2+{\mathrm{CO}}_2$

3.  ${\mathrm{N}}_2+{\mathrm{O}}_2+{\mathrm{C}}_2{\mathrm{H}}_6$

4.  ${\mathrm{N}}_2+{\mathrm{O}}_2+\mathrm{He}$

${\mathrm{O}}_3$ is absorbed by:

1.  Pyrogallol

2.  Menthol

3.  Turpentine oil

4.  Clove oil

Read the following statements (S) and Explanation (E). Choose the correct answers from the codes (1), (2), (3) and (4):

S : An element may have variable equivalent mass.

E : Such elements should possess variable valency. 

1.  S is correct but E is wrong
2.  S is wrong but E is correct
3.  Both S and E are correct and E is correct explanation of S
4.  Both S and E are correct but E is not correct explanation of S

0.5 g of fuming ${\mathrm{H}}_2{\mathrm{SO}}_4$ (oleum) is diluted with water. The solution requires 26.7 mL of 0.4 N $\mathrm{NaOH}$ for complete neutralization. Find the % of free ${\mathrm{SO}}_3$ in the sample of oleum. Also report % of oleum solution.

1. 104.68 %

2. 98 %

3. 106.13%

4. 56 %