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

Which of the following reagents will convert isobutyraldehyde to the corresponding acid?

$I. HNO_3$	$II. NH_2NH_2 / OH^-$
$III. 2[Ag(NH_3)_2]^+$	$IV. NaOH$

Which of the following compounds on reaction with ammoniacal silver nitrate solution forms a precipitate of silver?

The products $C$ and $D$ are given by the following reaction sequence:
$CH_3CH_2COCH_3$ $\xrightarrow[(ii) H_3O^+]{(i) CH_3MgBr} A$ $\xrightarrow[358 \ K]{20\% H_3PO_4} B \text{ (Major)}$ $\xrightarrow[(ii) Zn/H_2O]{(i) O_3} C + D$

An organic compound $B$ is formed by the reaction of ethylmagnesium iodide $(CH_3CH_2MgI)$ with a substance $A,$ followed by treatment with dilute aqueous acid. Compound $B$ does not react with $PCC$ in dichloromethane. Identify $A$.

Complete reaction of acetaldehyde with excess formaldehyde,upon heating with conc. $NaOH$ solution,gives $P$ and $Q$. Compound $P$ does not give Tollens' test,whereas $Q$ on acidification gives positive Tollens' test. Treatment of $P$ with excess cyclohexanone in the presence of catalytic amount of $p$-toluenesulfonic acid $(PTSA)$ gives product $R$. Sum of the number of methylene groups $(-CH_2-)$ and oxygen atoms in $R$ is....