In the given reaction,$A$ is:
$A$ $\xrightarrow{\text{Reduction}} B$ $\xrightarrow{HNO_2} C_2H_5OH$

The ratio of thermal conductivity of two rods of different materials is $5 : 4$. If the two rods have the same cross-sectional area and the same thermal resistance,what is the ratio of their lengths?

Which one of the following reactions does not occur?

The position of a particle at time $t$ is given by the equation $x(t) = \frac{v_0}{A}(1 - e^{-At})$,where $v_0$ is a constant and $A > 0$. The dimensions of $v_0$ and $A$ respectively are:

If $f: A \rightarrow B$ and $g: B \rightarrow C$ are two functions such that $g \circ f: A \rightarrow C$ is a bijection,then which one of the following is always true?

Let $R$ be a relation on a set $A$ such that $R = R^{-1}$,then $R$ is