The amount of water vapour produced by the complete combustion of 16 g of methane is:

1. 9 g
2. 18 g
3. 36 g
4. 27 g

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%

NaOH solution prepared by dissolving its 4 g in enough water to form 250 mL of the solution. The molarity of NaOH solution is-

1. 0.4 M

2. $\frac{1}{0.4}\mathrm{M}$

3. 0.8 M
4. $\frac{1}{0.8}\mathrm{M}$

Calculate the molality for a 3 M NaCl solution with a density of 1.25 g mL^–1.

1. 2.79 M

2. 1.79 M

3. 2 M

4. 1 M