A paramagnetic material has 10 ^ 28 atoms m ^ - 3 . Its magnetic...

From Curie's law, the magnetic susceptibility is inversely proportional to the temperature, i.e.,

$χ ∝ \dfrac{1}{T}$

Hence, the ratio of magnetic susceptibility at different temperature ${T}_{1} = 350K$ and ${T}_{2} = 300K$.

$\dfrac{{χ}_{2}}{{χ}_{1}} = \dfrac{{T}_{1}}{{T}_{2}}$

${χ}_{2} = {χ}_{1} \times \dfrac{{T}_{1}}{{T}_{2}} = 2 . 8 \times {10}^{- 4} \times \dfrac{350}{300}$

${χ}_{2} = 3 . 267 \times {10}^{- 4}$.