A mixture containing 2.3 g of formic acid (HCOOH) and 4.5 g of oxalic acid (H₂C₂O₄) is
heated with concentrated H₂SO₄. The gases evolved are passed through KOH pellets.

Calculate the mass of the gas that remains unabsorbed by KOH.

1.  1.4

2.  3.0

3.  2.8

4.  4.4

Calculate the mole fraction of the solute in a 1.00 m aqueous solution.

A mixture consists of hydrogen and oxygen gases in the mass ratio 1 : 4. Determine the mole ratio of hydrogen molecules to oxygen molecules present in the mixture.

Which of the following represents the volume occupied by a single water molecule, assuming the density of water is \(1\,\text{g cm}^{-3}\)?

1.  $9.0\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

2. $\mathrm{ 6}.023\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

3. $\mathrm{ 3}.0\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

4. $\mathrm{ 5}.5\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

What volume of oxygen gas is required for the complete combustion of 1 L of propane gas, C₃H₈, when both gases are measured at 0°C and 1 atm?
1. 7 L
2. 6 L
3. 5 L
4. 10 L

What is the number of moles of PbCl₂ formed when 6.5 g of PbO reacts with 3.2 g of HCl?

1. 0.044
2. 0.333
3. 0.011
4. 0.029

Which of the following volumes of concentrated H₂SO₄ (98% by mass, density = 1.80 g/mL) is required to prepare 1 L of 0.1 M H₂SO₄ solution?