Neurogenic heart is a characteristic of.......

Focal length of a convex lens will be maximum for

Assertion $(A)$: $A$ catalyst increases the rate of a reaction.
Reason $(R)$: In the presence of a catalyst,the activation energy of the reaction increases.
The correct answer is

Conifers differ from grasses in the

$1\, kg$ of a diatomic gas is at a pressure of $8 \times 10^4\, N/m^2$. The density of the gas is $4\, kg/m^3$. What is the energy of the gas due to its thermal motion?

$A$ and $B$ are two concentric circular loops carrying currents $i_1$ and $i_2$ as shown in the figure. If the ratio of their radii is $1:2$ and the ratio of the magnetic flux densities at the centre $O$ due to $A$ and $B$ is $1:3$,then the value of $\frac{i_1}{i_2}$ will be