Which of the following gives Fehling's solution test?

Identify $R', R''$ and $R'''$ for the following reaction: $R'R''C=O \xrightarrow{(i) R'''MgX, (ii) H_2O} 2-methylbutane-2-ol$

Compound '$X$' (molecular formula $C_3H_8O$) reacts with acidic potassium dichromate to give product '$Y$' (molecular formula $C_3H_6O$). '$Y$' gives a silver mirror test. When '$Y$' is reacted with aqueous $NH_2CONHNH_2$ and sodium acetate,it gives product '$Z$'. What is the structure of '$Z$'?

Benzaldehyde reacts with ammonia to form

$A$ compound $A$ with molecular formula $C_{10}H_{13}Cl$ gives a white precipitate on adding silver nitrate solution. $A$ on reacting with alcoholic $KOH$ gives compound $B$ as the main product. $B$ on ozonolysis gives $C$ and $D$. $C$ gives Cannizzaro reaction but not aldol condensation. $D$ gives aldol condensation but not Cannizzaro reaction. $A$ is:

The increasing order of the following compounds towards $HCN$ addition is: