$RR-21$ is a high-yielding variety of:

$A$ lift is moving downwards with an acceleration equal to the acceleration due to gravity. $A$ body of mass $M$ kept on the floor of the lift is pulled horizontally. If the coefficient of friction is $\mu$,then the frictional resistance offered by the body is:

Which of the following statements is not correct?

Which of the following proteins is insoluble in any solvent?

If three unit vectors $\overrightarrow{a}, \overrightarrow{b}, \overrightarrow{c}$ satisfy $\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}=\overrightarrow{0}$, then the angle between $\overrightarrow{a}$ and $\overrightarrow{b}$ is

The relation "congruence modulo $m$" is