Which from following solids is isotropic?

Calculate $\Delta \mathrm{S}_{\text {total }}$ for a certain reaction at 298 K if $\Delta \mathrm{H}^{\circ}=-208.6 \mathrm{~kJ}$ and $\Delta \mathrm{S}^{\circ}=-36 \mathrm{~J} \mathrm{~K}^{-1}$

Which among the following is benzylic halide?

Which from following is correct regarding $t_{1 / 2}$ of reaction if we double the initial concentration of a reactant in first order reaction?