Which of the following samples contains the  maximum number of water molecules?

1. 18 mL of water 
2. 0.18 g of water 
3. 0.00224 L water vapours at 1 atm and 273 K
4. 10^-3 mol of water 

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?

What is the number of moles of O-atom in 126 amu of ${\mathrm{HNO}}_3$?

1.  2

2.  $\frac{2}{{\mathrm{N}}_{\mathrm{A}}}$

3.  6

4.  $\frac{6}{{\mathrm{N}}_{\mathrm{A}}}$