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:

1.	35.5	2.	28.1
3.	128	4.	19.0

100 mL of H₂SO₄ solution having molarity 1 M and density 1.5 g mL⁻¹ is mixed with 400 mL water.
If the density of the final solution is 1.25 g mL⁻¹, calculate the molarity of the final H₂SO₄ solution.

25.3 g of sodium carbonate, Na₂CO₃, is dissolved in enough water to make 250 mL of a solution. If sodium carbonate completely dissociates, the molar concentrations of sodium ion, Na⁺ and carbonate ion, $C{O}_3^{2-}$are respectively:
(molar mass of Na₂CO₃ = 106g mol^-1)

1. 0.955 M and 1.910 M
2. 1.910 M and 0.955 M
3. 1.90 M and 1.910 M
4. 0.477 M and 0.477 M

The volume of oxygen gas (O₂) needed to completely burn 1 L of propane gas (C₃H₈)  (both O₂ & propane measured at 0°C and 1 atm) will be:
1. 7 L
2. 6 L
3. 5 L
4. 10 L

An organic compound contains carbon, hydrogen, and oxygen. If elemental analysis reveals 38.71% carbon and 9.67% hydrogen, which of the following is its empirical formula?

An organic substance containing C, H, and O gave the following percentage composition :

C = 40.687%, H = 5.085% and O = 54.228%. The vapour density of this organic substance is 59.

The molecular formula of the compound will be:

1. C₄H₆O₄

2. C₄H₆O₂

3. C₄H₄O₂

4. None of the above

An aqueous solution of NaOH has a molarity of 2 M and a density of 1.28 g cm⁻³.
Calculate the molality of the solution:
[Given: Molecular mass of NaOH = 40 g mol^-1]

What is the ratio of the number of atoms in 2.2 g of CO₂ and in 1.7 g of NH₃?

The molality of a 20% (by mass) CaCO₃ solution is : 
(Given: Density of solution is 1.2 gm/ml)