Which of the following statements is correct?

(a) With neutral conditions at room temperature, a diketone is formed via the hydroxylation reaction.

(b) Under neutral or alkaline conditions at higher temperatures, the triple bond is cleaved to give carboxylic acids.

${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{C}\equiv \mathrm{C}{\left({\mathrm{CH}}_2\right)}_2{\mathrm{CH}}_3\stackrel{\left[\mathrm{O}\right]}{\to }{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{COOH}+\mathrm{HOOC}{\left({\mathrm{CH}}_2\right)}_2{\mathrm{CH}}_3$

( c) The addition of HBr proceeds via the formation of carbocation.

Allylic carbocation is more stable due to resonance

Its formation requires lesser $\mathrm{\Delta }{H}^{‡}$ as compared to 2° carbocation and hence is formed at a faster rate.

(d) The additions may be depicted as follows.

The conversion allylic carbocation $\to$ 1,2-adduct involves a lower $\mathrm{\Delta }{H}^{‡}$ as compared to carbocation $\to$1,4-adduct. At low temperature, 1,2-adduct is formed due to the lower $\mathrm{\Delta }{H}^{‡}$. Thus, it formation is kinetically-controlled. As temperature is raised, 1,2-adduct passes over to the allylic carbocation and then to thermodynamically more stable 1,4-adduct. The 1,4-adduct is more stable as it is a more substituted alkene. Once, 1,4-adduct is formed, it cannot be converted to 1 ,2-adduct on lowering temperature as the conversion of 1 ,4-adduct to intermediate complex involves a larger $\mathrm{\Delta }{H}^{‡}$ value.