Which of the following has the greatest number of molecules?

1. 64 g SO₂ 

2. 44 g CO₂

3. 48 g O₃ 

4. 8 g H₂

Concentrated aqueous sulphuric acid is 98% H₂SO₄ by mass and has a density of 1.80 g mL^-1. The volume of acid required to make one litre of 0.1 M H₂SO₄ solution is:

1. 11.10 mL

2. 16.65 mL

3. 22.20 mL

4. 5.55 mL

The moles of lead (II) chloride that will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl are:
1. 0.044
2. 0.333
3. 0.011
4. 0.029

An organic compound contains carbon, hydrogen, and oxygen. If elemental analysis reveals 38.71% carbon and 9.67% hydrogen, which of the following is its empirical formula?

The volume of oxygen gas (O₂) needed to completely burn 1 L of propane gas (C₃H₈)  (both O₂ & propane measured at 0°C and 1 atm) will be:
1. 7 L
2. 6 L
3. 5 L
4. 10 L

The volume occupied by one water molecule (density = 1 g cm^-3) is:

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

2. $6.023\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

3. $3.0\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

4. $5.5\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

10 g of hydrogen and 64 of oxygen were filled in a steel vessel and exploded. The amount of water produced in this reaction will be:

1. 2 mol

2. 3 mol

3. 4 mol

4. 1 mol

The number of atoms in 0.1 mole of a triatomic gas is (N_A= 6.02 x 10²³ mol^-1):

1. $6.026\times {10}^{22}$

2. $1.806\times {10}^{23}$

3. $3.600\times {10}^{23}$

4. $1.800\times {10}^{22}$

25.3 g of sodium carbonate, Na₂CO₃, is dissolved in enough water to make 250 mL of a solution. If sodium carbonate completely dissociates, the molar concentrations of sodium ion, Na⁺ and carbonate ion, $C{O}_3^{2-}$are respectively:
(molar mass of Na₂CO₃ = 106g mol^-1)

1. 0.955 M and 1.910 M
2. 1.910 M and 0.955 M
3. 1.90 M and 1.910 M
4. 0.477 M and 0.477 M