Which of the following is a characteristic of $Pteridophytes$?

$1\, g$ of hydrogen is converted into $0.993\, g$ of helium in a thermonuclear reaction. The energy released is

Consider the following statements $A$ and $B$. Identify the correct choice in the given answer.
$A$. $p-n, p-p$ and $n-n$ forces between nucleons are not equal and charge dependent.
$B$. In a nuclear reactor,the fission reaction will be in an accelerating state if the value of the neutron reproduction factor $k > 1$.

An ideal transformer has $100$ turns in the primary and $250$ turns in the secondary. The peak value of the $AC$ voltage in the primary is $28\ V$. The $r.m.s.$ secondary voltage is nearest to $....V$.

In the following reaction,$X$ and $Y$ respectively are:
$C_2H_5OH \xrightarrow{KMnO_4 / H^{+}} X$
$X \xrightarrow[H_2SO_4 / \Delta]{Y} CH_3COOC_2H_5$

$A$ circular disc of radius $R$ is removed from a bigger circular disc of radius $2R$ such that the circumferences of the discs touch. The centre of mass of the new disc is at a distance $\alpha R$ from the centre of the bigger disc. The value of $\alpha$ is