Which from following methods of structural formula representation uses conventionally a point for front carbon and a circle around it for rear carbon?

Identify substrate '$$\mathrm{A}$$' in the following sequence of reactions.

A $$\mathrm{\mathrel{\mathop{\kern0pt\longrightarrow} \limits_\Delta ^{SOC{l_2}}}}$$ B $$\mathrm{\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{{C_2}{H_5}Cl}^{Na/ether}}}$$ 2-Methylbutane

Which of the following is tertiary benzylic alcohol?

Which among the following is a feature of $$\mathrm{S}_{\mathrm{N}} 1$$ mechanism?