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

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

What is the concentration of a urea solution if 6.02×10²⁰ molecules of urea are present in 100 mL of the solution?

The molality of a 15% (w/vol.) solution of H₂SO₄ of density 1.1g/cm³ is:

1. 1.2 mol/kg

2. 1.4 mol/kg

3. 1.8 mol/kg

4. 1.6 mol/kg

Which mode of expressing concentration is independent of temperature?

1. Molality

2. Percent by mass

3. Mole fraction

4. All of the above