Urotropine is

Which of the following will give a yellow precipitate with $I_2/NaOH$?

$CH_3-C(O)-CH_2-CH_2-CH_2-CH_2-CHO \xrightarrow{HO^{-} / \Delta} (A) (73\%)$
Product $(A)$ is

An optically active compound $C_6H_{12}O$ gives a positive test with $2,4-$dinitrophenylhydrazine,but a negative test with Tollens' reagent. What is the structure of the compound?

Match the reactions in Column-$I$ with their products in Column-$II$.
| Column-$I$ (Reagents) | Column-$II$ (Product) |
| :--- | :--- |
| $(A) \ CH_3CHO + 2C_2H_5OH \xrightarrow{HCl_{(g)}} $ | $(i) \ (CH_3)_2C(OCH_2)_2$ |
| $(B) \ CH_3COCH_3 + CH_2OH-CH_2OH \xrightarrow{HCl_{(g)}} $ | $(ii) \ CH_3CH(OH)CN$ |
| $(C) \ CH_3CHO + HCN$ $\xrightarrow{OH^-}$ $\xrightarrow{H_3O^+}$ | $(iii) \ CH_3CH(OC_2H_5)_2$ |
| $(D) \ CH_3CHO + HCN \xrightarrow{OH^-} $ | $(iv) \ CH_3CH(OH)COOH$ |

In the Cannizzaro reaction given below,the slowest step is $:-$
$2Ph-CHO \xrightarrow{\stackrel{\ominus}{O}H} PhCH_2OH + PhCO_2^{\ominus}$