The oxidation number of $C$ in $HNC$ is .......

If the mean of a Poisson distribution is $\frac{1}{2}$,then the ratio of $P(X=3)$ to $P(X=2)$ is

Coordination compounds have great importance in biological systems. In this context,which of the following statements is incorrect?

Chitin is an example of which of the following?

Which pair of substances gives the same gaseous product when they react with water?

$A$ meter bridge is set up as shown to determine end corrections at $A$ and $B$. When a resistance of $15 \ \Omega$ is used in the left gap and $20 \ \Omega$ in the right gap,the null point is obtained at a distance of $42 \ cm$ from $A$. When these resistances are interchanged,the null point is obtained at a distance of $57 \ cm$ from $A$. The values of the end corrections are: