Boron in green plants assists in

The value of $\cos \frac{2 \pi}{15} \cos \frac{4 \pi}{15} \cos \frac{8 \pi}{15} \cos \frac{14 \pi}{15}$ is :

Corrosion of iron is essentially an electrochemical phenomenon where the cell reactions are

When acetamide reacts with $Br_2$ and caustic soda,then we get:

Assertion $(A)$ At $300 \ K$,kinetic energy of $16 \ g$ of methane is equal to the kinetic energy of $32 \ g$ of oxygen.
Reason $(R)$ At constant temperature,kinetic energy of one mole of all gases is equal.

$M_p$ denotes the mass of a proton and $M_n$ denotes the mass of a neutron. $A$ given nucleus,of binding energy $B$,contains $Z$ protons and $N$ neutrons. The mass $M(N, Z)$ of the nucleus is given by ($c$ is the velocity of light):