The composition of a carbon dioxide (CO₂) molecule is one atom of ¹²C and two atoms of ¹⁶O - AQA - A-Level Physics - Question 10 - 2017 - Paper 2

Given that 2.2 kg of CO₂ is equal to 2200 g:

$ext{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} = \frac{2200 g}{44 g/mol} = 50 \text{ moles}$

Using Avogadro's number, which is approximately (6.022 \times 10^{23}) molecules per mole:

$\text{Number of molecules} = \text{Number of moles} \times \text{Avogadro's number}$

So,

$\text{Number of molecules} = 50 \times 6.022 \times 10^{23} \approx 3.011 \times 10^{25} \text{ molecules}$

The closest answer to the calculated number of molecules (approximately (3.011 \times 10^{25})) is option C: $3.0 \times 10^{25}$.