If $A$ and $B$ are square matrices of order $3$, $A$ is non-singular, and $AB = O$, then $B$ is a:

$A$ person in an elevator accelerating upwards with an acceleration of $2\,m s^{-2}$ tosses a coin vertically upwards with a speed of $20\,m s^{-1}$. After how much time will the coin fall back into his hand? $(g = 10\,m s^{-2})$

Which of the following is $NOT$ a type of sexual reproduction in fungi?

The principle of immunization or vaccination is based on the property of ..........

If $y = \sec(\tan^{-1}x)$,then $\frac{dy}{dx}$ at $x = 1$ is equal to:

$A$ stationary wave is represented by $y = 10 \sin \frac{\pi x}{4} \cos 20 \pi t$,where $x$ and $y$ are expressed in $cm$ and $t$ in seconds. The distance between two consecutive nodes is: (in $cm$)