\(\Delta U = T \Delta A\)
Use volume conservation as,
\(2 \times \frac{4}{3} \pi(1)^{3}=\frac{4}{3} \pi R ^{3}\)
\(R =2^{1 / 3}\)
Substitute the values in the energy expression as,
\(\Delta U = T \Delta A\)
\(=(0.1) \times 4 \pi\left(1^{2}-\left(2^{1 / 3}\right)^{2}\right)\)
\(=4 \pi\left(0.41 \times 10^{-6}\right) J\)
\(=0.52 \mu J\)
$\left(g=10\, ms ^{-2}\right)$