The hydrated salt Na₂SO₄.nH₂O, undergoes 55% loss in weight on heating and becomes anhydrous. The value of n will be -

1. 5

2. 3

3. 7

4. 10

10 g of a silver coin when dissolved completely in
excess of conc. HNO${}_3$ gives 8.5 g of silver nitrate.
The percentage purity of the coin is

1. 25%

2. 54%

3. 67%

4. 100%

The molality of pure water is: 

1. 1 m

2. 18 m

3. 55.5 m

4. None of the above

At 100 ºC and 1 atm, if the density of liquid water is 1.0 g cm^–3 and that of water vapor is 0.0006 g cm^-3, then the volume occupied by water molecules in 1 litre of steam at that temperature will be:

A bottle of ${\mathrm{H}}_3{\mathrm{PO}}_4$ solution contains 70% (w/w) acid. If the density of the solution is 1.54 g ${\mathrm{cm}}^{-3}$, the volume of the ${\mathrm{H}}_3{\mathrm{PO}}_4$ solution required to prepare 1 L of 1 N solution is

1.  90mL

2.  45 mL

3.  30 mL

4.  23 mL

The density of a 2 M aqueous solution of NaOH is 1.28 g/$c{m}^3$. The molality of the solution is: 
[molecular mass of NaOH = 40 $gmo{l}^{-1}$]

Calculate the mass of $\mathrm{CaO}$ required to remove the hardness of ${10}^6$ litre of water containing 1.62 g of calcium bicarbonate per litre.

1. 5.6*10^-6 

2. 5.6*10^5

3. 4.8*10^9

4. 1.2*10^-4

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 %

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

${\mathrm{O}}_3$ is absorbed by:

1.  Pyrogallol

2.  Menthol

3.  Turpentine oil

4.  Clove oil