What is the process of breeding crops to increase their levels of minerals,vitamins,and proteins called?

$A$ potentiometer consists of a wire of length $4\, m$ and resistance $10\,\Omega$. It is connected to a cell of $emf$ $2\, V$. The potential difference per unit length of the wire will be ............ $V/m$.

Which of the following is considered a hotspot of biodiversity in India?

$50 \, g$ 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 $= 4200 \, J \, kg^{-1} \, ^\circ C^{-1}$)

Two coaxial solenoids of different radii carry current $I$ in the same direction. Let $\vec{F}_1$ be the magnetic force on the inner solenoid due to the outer one and $\vec{F}_2$ be the magnetic force on the outer solenoid due to the inner one. Then:

What does the given experimental set-up depict?
Choose the correct option accordingly.