From which plant did $D.J. Ivanowsky$ discover viruses?

The absolute configurations of the two chiral centers in the following molecule are:

Which of the following is a level of biological organization?

$A$ conveyor belt is moving at a constant speed of $2\, m/s$. $A$ box is gently dropped on it. The coefficient of friction between them is $\mu = 0.5$. The distance that the box will move relative to the belt before coming to rest on it,taking $g = 10\, m/s^2$,is ........ $m$.

When a glass prism of refracting angle $60^{\circ}$ is immersed in a liquid,its angle of minimum deviation is $30^{\circ}$. The critical angle of glass with respect to the liquid medium is (in $^{\circ}$)

An aircraft executes a horizontal loop of radius $9 \ km$ at a constant speed of $540 \ km/h$. The wings of the aircraft are banked at an angle of (Acceleration due to gravity $g = 10 \ m/s^2$):