Arrange the following substrate in decreasing order of electrophilic addition reaction

Which of the following is a natural polymer?

$A$ random variable $X$ has the following probability distribution:

$X = x_i$	$-2$	$-1$	$0$	$1$	$2$
$P(X = x_i)$	$\frac{1}{6}$	$k$	$\frac{1}{4}$	$k$	$\frac{1}{6}$

The variance of this random variable is:

In the figure shown,for given values of $R_1$ and $R_2$,the balance point for the jockey is at $40\, cm$ from $A$. When $R_2$ is shunted by a resistance of $10\,\Omega$,the balance point shifts to $50\, cm$. Find $R_1$ and $R_2$ $(AB = 1\, m)$.

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

Which final cytochrome in the respiratory chain donates electrons to oxygen?