What happens when $D-glucose$ is treated with the following reagents?
$(i)$ $HI$
$(ii)$ Bromine water
$(iii)$ $HNO_3$

(N/A) $(i)$ When $D-glucose$ is heated with $HI$ for a long time,$n-hexane$ is formed.
$CHO-(CHOH)_4-CH_2OH \xrightarrow[\Delta]{HI} CH_3-CH_2-CH_2-CH_2-CH_2-CH_3$
$(ii)$ When $D-glucose$ is treated with $Br_2$ water,$D-gluconic$ acid is produced.
$CHO-(CHOH)_4-CH_2OH \xrightarrow{Br_2 \text{ water}} COOH-(CHOH)_4-CH_2OH$
$(iii)$ On being treated with $HNO_3$,$D-glucose$ gets oxidised to give saccharic acid (glucaric acid).
$CHO-(CHOH)_4-CH_2OH \xrightarrow{HNO_3} COOH-(CHOH)_4-COOH$