The power dissipated in the circuit shown in the figure is $30 \, W$. The value of $R$ is ............. $\Omega$.

The first,second and third Ionisation energies ($E_1, E_2$ and $E_3$) for an element are $7 \ eV, 12.5 \ eV$ and $42.5 \ eV$ respectively. The most stable oxidation state of the element will be

$K_1, K_2$ and $K_3$ are the equilibrium constants of the following reactions $(I), (II)$ and $(III)$,respectively :
$(I) \ N_2 + 2O_2 \rightleftharpoons 2NO_2$
$(II) \ 2NO_2 \rightleftharpoons N_2 + 2O_2$
$(III) \ NO_2 \rightleftharpoons \frac{1}{2}N_2 + O_2$
The correct relation from the following is

Two bodies $A$ and $B$ of equal surface area have thermal emissivities of $0.01$ and $0.81$ respectively. The two bodies are radiating energy at the same rate. Maximum energy is radiated from the two bodies $A$ and $B$ at wavelengths $\lambda_A$ and $\lambda_B$ respectively. The difference in these two wavelengths is $1 \mu m$. If the temperature of the body $A$ is $5802 \ K$,then the value of $\lambda_B$ is:

Chrysophytes,Euglenoids,Dinoflagellates,and Slime moulds are included in the kingdom:

Keystone species deserve protection because these