In which of the following reactions,$MgO$ is not formed?

The probability that a student is not a swimmer is $1/5$. What is the probability that $4$ out of $5$ students are swimmers?

Which of the following graphs represents uniform motion?

If a body dropped freely from a height of $20 ~m$ reaches the surface of a planet with a velocity of $31.4 ~ms^{-1}$,then the length of a simple pendulum that ticks seconds on the planet is (in $~m$)

The foot of the perpendicular from $(0,2,3)$ to the line $\frac{x+3}{5}=\frac{y-1}{2}=\frac{z+4}{3}$ is

Which of the following compounds is an optically inactive compound?