$$ \text { Consider the following two reactions } \mathrm{A} \text { and } \mathrm{B} \text {. } $$

Numerical value of [molar mass of $x+$ molar mass of $y$ ] is $\_\_\_\_$

$$ \text { Arrange the following carbanions in the decreasing order of stability. } $$

Choose the correct answer from the options given below :

At $27^{\circ} \mathrm{C}$ in presence of a catalyst, activation energy of a reaction is lowered by $10 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The logarithm of ratio of $\frac{\mathrm{k} \text { (catalysed) }}{\mathrm{k} \text { (uncatalysed) }}$ is….

(Consider that the frequency factor for both the reactions is same)

A student is given one compound among the following compounds that gives positive test with Tollen's reagent.

The compound is :