Which hormone is responsible for apical dominance?

If $A = \begin{bmatrix} -8 & 5 \\ 2 & 4 \end{bmatrix}$ satisfies the equation $x^2 + 4x - p = 0$,then $p$ is equal to

The acceleration of a moving body can be found from

Which country produces the maximum amount of greenhouse gases?

If one of the lines of the pair of straight lines $ax^2 + 2hxy + by^2 = 0$ bisects the angle between the coordinate axes,then:

$A$ and $B$ are two substances undergoing radioactive decay in a container. The half-life of $A$ is $15 \ min$ and that of $B$ is $5 \ min$. If the initial concentration of $B$ is $4$ times that of $A$ and they both start decaying at the same time,how much time will it take for the concentration of both of them to be same? $.......... \ min$