The mole fraction of the solute in a 1.00 molal aqueous solution is: 

Find the mass of CaCO₃ required to completely react with 25 mL of 0.75 M HCl according to the reaction:

CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + CO₂(g) + H₂O(l)

1. 0.36 g

2. 0.09 g

3. 0.96 g

4. 0.66 g

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]

Concentrated nitric acid is 70% HNO₃. The amount of concentrated nitric acid solution that should be used to prepare 250 mL of 2.0 M HNO₃ would be:

1. 90.0 g conc. HNO₃
2. 70.0 g conc. HNO₃
3. 54.0 g conc. HNO₃
4. 45.0 g conc. HNO₃

A solution is prepared by adding 2 g of substance A to 18 g of water. The mass percent of the solute is:

1. 20%

2. 10%

3. 15%

4. 18%

An aqueous solution contains 18 g of urea in 1500 cm³ of solution.
If the density of the solution is 1.052 g cm⁻³ and the molar mass of urea is 60 g mol⁻¹,
calculate the molality of the solution.
1. 0.2
2. 0.192
3. 0.064
4. 1.2

Sulphuric acid reacts with sodium hydroxide according to the reaction:

${\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{NaOH}\to {\mathrm{Na}}_2{\mathrm{SO}}_4+2{\mathrm{H}}_2\mathrm{O}$

When 1L of 0.1 M sulphuric acid solution is allowed to react with 1 L of 0.1 M sodium hydroxide solution, the amount of sodium sulphate formed and its molarity in the solution obtained are respectively-

Find the mass of NaNO₃ required to prepare 50 mL of aqueous solution containing 70.0 mg Na⁺ per mL.
(Round off to the nearest integer.
Given: Na = 23, N = 14, O = 16)