$A$ compound contains $69.5\%$ oxygen and $30.5\%$ nitrogen and its molecular weight is $92$. The formula of that compound is

Seven balls are drawn simultaneously from a bag containing $5$ white and $6$ green balls. The probability of drawing $3$ white and $4$ green balls is:

The number of ways of arranging $8$ men and $4$ women around a circular table such that no two women can sit together is

There is a uniform electric field of strength $10^3 \, V/m$ along the $y$-axis. $A$ body of mass $1 \, g$ and charge $10^{-6} \, C$ is projected into the field from the origin along the positive $x$-axis with a velocity of $10 \, m/s$. Its speed in $m/s$ after $10 \, s$ is (Neglect gravitation).

The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true?

'Amoebiasis' (amoebic dysentery) is caused by