Which from following molecules has trigonal planar geometry?

Which from following polymers is grouped under elastomers?

What type of following compounds is obtained in first step of Wolf-Kishner reduction of carbonyl compounds?

The reaction $2 \mathrm{~A}+\mathrm{B}+\mathrm{C} \longrightarrow \mathrm{D}+\mathrm{E}$ is found to be first order in A , second order in B and zero order in C . What is the effect of increasing concentration of all reactants twice?