If $\tan A + \cot A = 4,$ then $\tan^4 A + \cot^4 A$ is equal to

$50 \, g$ of copper is heated to increase its temperature by $10 \, ^\circ C$. If the same quantity of heat is given to $10 \, g$ of water,the rise in its temperature is ........ $^\circ C$. (Specific heat of copper $= 420 \, J \, kg^{-1} \, ^\circ C^{-1}$,Specific heat of water $= 4200 \, J \, kg^{-1} \, ^\circ C^{-1}$)

Which one of the following does not involve coagulation?

Production of a human protein in bacteria by genetic engineering is possible because

Water is being poured at the rate of $36 \ m^3 / min$ into a cylindrical vessel,whose circular base has a radius of $3 \ m$. Then the water level in the cylinder is rising at the rate of:

Dettol is an example of