Which one of the following generally acts as an antagonist to gibberellins?

The pattern of standing waves formed on a stretched string at two instants of time (extreme and mean positions) is shown in the figure. The velocity of the two waves superimposing to form stationary waves is $360 \ m/s$ and their frequency is $256 \ Hz$. Which of the following is not a possible value of $t$ (in $sec$)?

Match column-$I$ with column-$II$ and choose the correct combination from the options given below.

Column-$I$	Column-$II$
$A$. National Botanical Research Institute	$I$. Carolus Linnaeus
$B$. Indian Botanical Garden	$II$. Taxon
$C$. Binomial Nomenclature	$III$. Howrah (India)
$D$. $A$ unit of Classification	$IV$. Lucknow

If $\frac{1}{x(x^2 + 1)} = \frac{A}{x} + \frac{Bx + C}{x^2 + 1}$,then $(A, B, C) = $

There are two wires of the same material and same length. If the diameter of the second wire is $2$ times the diameter of the first wire,then the ratio of the extension produced in the wires by applying the same load will be:

$3$ moles of ethanol react with $1$ mole of phosphorus tribromide to form $3$ moles of bromoethane and $1$ mole of $X$. Which of the following is $X$?