CHEMISTRY TRIAL & LIKELY QUESTIONS UNDER THE PREDICTED AREAS/TOPICS Application of the Mass Spectrometer Bonding Electronegativity and Ionization Energy Hybridization Mole Concept Calculations

The atomic mass of Carbon (C) is approximately $12.01 \text{ g/mol}$.
The atomic mass of Oxygen (O) is approximately $16.00 \text{ g/mol}$.

$\text{moles} = \frac{\text{mass}}{\text{molar mass}}$.

Rounding to a reasonable number of significant figures:
The number of moles in 44 g of CO₂ is $\boxed{\text{1.00 mol}}$.

2. Determine the mass of 0.5 mole of H₂SO₄.

The atomic mass of Hydrogen (H) is approximately $1.01 \text{ g/mol}$.
The atomic mass of Sulfur (S) is approximately $32.07 \text{ g/mol}$.
The atomic mass of Oxygen (O) is approximately $16.00 \text{ g/mol}$.

$\text{mass} = \text{moles} \times \text{molar mass}$.

The mass of 0.5 mole of H₂SO₄ is $\boxed{\text{49.05 g}}$.

3. Calculate the number of molecules in 2 moles of oxygen.

Avogadro's number is $6.022 \times 10^{23} \text{ molecules/mol}$.

$\text{number of molecules} = \text{moles} \times \text{Avogadro's number}$.
Oxygen gas exists as diatomic molecules, O₂.

The number of molecules in 2 moles of oxygen is $\boxed{1.204 \times 10^{24} \text{ molecules}}$.

4. What volume will 0.25 mole of a gas occupy at s.t.p.?

At Standard Temperature and Pressure (s.t.p.), 1 mole of any ideal gas occupies $22.4 \text{ dm}^3$ (or $22.4 \text{ L}$).

$\text{volume} = \text{moles} \times \text{molar volume at s.t.p.}$.

The volume occupied by 0.25 mole of a gas at s.t.p. is $\boxed{5.6 \text{ dm}^3}$.