The correct order of ionisation energy of $C, N, O, F$ is

If $A$ is an invertible matrix of order $n$,then the determinant of $\operatorname{adj} A$ is equal to :

Which one of the following is a secondary alcohol?

Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason : According to classical physics,all moving electrons radiate.

Solution $X$ contains $Na_2CO_3$ and $NaHCO_3$. $20 \ mL$ of $X$ when titrated using methyl orange indicator consumed $60 \ mL$ of $0.1 \ M$ $HCl$ solution. In another experiment,$20 \ mL$ of $X$ solution when titrated using phenolphthalein consumed $20 \ mL$ of $0.1 \ M$ $HCl$ solution. The concentrations (in $mol \ L^{-1}$) of $Na_2CO_3$ and $NaHCO_3$ in $X$ are respectively:

$A$ soap bubble,having a radius of $1 \ mm$,is blown from a detergent solution having a surface tension of $2.5 \times 10^{-2} \ N/m$. The pressure inside the bubble is equal to the pressure at a point $Z_0$ below the free surface of water in a container. Taking $g = 10 \ m/s^2$ and the density of water $\rho = 10^3 \ kg/m^3$,the value of $Z_0$ is: (in $cm$)