Assertion $(\mathrm{A})\left[\mathrm{B}\left(\mathrm{OH}_2\right)_6\right]^{3+}$ and $\left[\mathrm{B}(\mathrm{OH})_4\right]^{-}$form octahedral and tetrahedral structures.

Reason (R) Being electron deficient, boron readily reacts with Lewis bases like $\mathrm{H}_2 \mathrm{O}, \mathrm{OH}^{-}$ The correct option among the following is

The minimum temperature required for a non-catalytic reaction between $\mathrm{N}_2$ and $\mathrm{O}_2$ is

Assertion (A) Both rhombic and monoclinic sulphur have $\mathrm{S}_8$ molecules.

Reason (R) They have planar structure.

The correct option among the following is

The chemical structures of $\mathrm{XeO}_3$ and $\mathrm{XeOF}_4$, respectively, are