Which of the following will not yield an acid anhydride?

$\mathrm{t}-\mathrm{butyl}-\mathrm{CH}=\mathrm{CH}-\mathrm{COOH}$

can't give the decarboxylation reaction, while normally, $\mathrm{\alpha }-\mathrm{\beta }$ unsaturated acid gives this reaction because

A cyclic compound that gives succinic acid on oxidative cleavage is-

Which of the following acids will undergo decarboxylation easily?

${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}\stackrel{{\mathrm{PCl}}_5}{⟶}\mathrm{A}+{\mathrm{POCl}}_3+\mathrm{HCl}$ . Compound $\mathrm{A}$ can also be formed by treating chlorine with the following compound in the absence of a halogen carrier-

Which of the following decolourises the colour of acidic ${\mathrm{KMnO}}_4$?