What is the product formed when chloroform reacts with concentrated $HNO_3$?

The increasing order of reduction of alkyl halides with zinc and dil. $HCl$ is:

The rate of $S_{N}1$ reaction for the given compounds is:

Vinyl chloride reacts with $HCl$ to form

Phosgene is formed slowly from which one of the following on exposure to air and sunlight?

When $3-$methylbutan$-2-$ol is treated with $HBr$,the following reaction takes place:
$CH_3-CH(CH_3)-CH(OH)-CH_3 \xrightarrow{HBr} CH_3-C(Br)(CH_3)-CH_2-CH_3$
Give a mechanism for this reaction.
(Hint : The secondary carbocation formed in step $II$ rearranges to a more stable tertiary carbocation by a hydride ion shift from $3^{rd}$ carbon atom.)