Keystone species deserve protection because these

$A$ nucleus ruptures into two nuclear parts which have their velocity ratio equal to $2 : 1$. What will be the ratio of their nuclear size (nuclear radius)?

Find the binomial probability distribution whose mean is $3$ and variance is $2$.

Let $R_1$ be a relation defined by $R_1 = \{(a, b) | a \geq b, a, b \in \mathbb{R}\}$. Then $R_1$ is

Observe the following statements :
$I$. Bleaching powder is used in the preparation of chloroform.
$II$. Bleaching powder decomposes in the presence of $CoCl_2$ to liberate $O_2$.
$III$. Aqueous $KHF_2$ is used in the preparation of fluorine.
The correct combination is :

With what minimum velocity should a block of mass $m$ be projected from the left end $A$ towards end $B$ such that it reaches the other end $B$ of a conveyor belt of length $L$ moving with a constant velocity $v$ in the opposite direction? The friction coefficient between the block and the belt is $\mu$.