If the mean of the data $7, 8, 9, 7, 8, 7, \lambda, 8$ is $8$,then the variance of this data is

If a set $A$ has $n$ elements,then the total number of subsets of $A$ is:

Observe the following statements:
$A$. Integrating factor of $\frac{dy}{dx} + y = x^2$ is $e^x$.
$R$. Integrating factor of $\frac{dy}{dx} + P(x)y = Q(x)$ is $e^{\int P(x) dx}$.
Then,the true statement among the following is:

Which of the following is paramagnetic and contains a three-electron bond in its structure?

The negation of the statement pattern $\sim p \vee (q \rightarrow \sim r)$ is

Two rotating bodies $A$ and $B$ of masses $m$ and $2m$ with moments of inertia $I_A$ and $I_B$ $(I_B > I_A)$ have equal kinetic energy of rotation. If $L_A$ and $L_B$ are their angular momenta respectively,then: