Question

The energy required for the ionisation of 0.02 gram atom of magnesium is $x$ kJ. The amount of energy required to ionise 1 atom of magnesium is:

• A. $x$ kJ
• B. $\frac{x}{0.02N_A}$J
• C. $\frac{x\times {10}^3}{0.02N_A}$J
• D. $x{N}_{A}kJ$

Answer 1

The correct option is C $\frac{x\times {10}^3}{0.02N_A}$J

Molecular mass of $Mg=24$

no. of moles $=\frac{0.02}{24\times 100}=\frac{1}{1200}$

no. of atoms $=\frac{N_A}{1200}$

$\left(\frac{N_A}{1200}\right)$ atoms require energy $x$ by (given)

$\therefore$ Energy to ionise $1$ atom $=\frac{x}{\left(\frac{N_A}{1200}\right)}kJ$

$=\frac{x\times {10}^3}{\left(N_A\right)\left(\frac{1}{1200}\right)}J$

$=\frac{x\times {10}^3}{0.02N_A}$ Joules