Which one of the following is a correct set?

$A$ small square loop of wire of side $l$ is placed inside a large square loop of wire of side $L$ $(L \gg l)$. The loops are coplanar and their centers coincide. The mutual inductance of the system is proportional to

$A$ conducting rod $PQ$ of length $5\,m$ oriented as shown in the figure is moving with a velocity $\vec{v} = (2\,m/s)\hat{i}$ without any rotation in a uniform magnetic field $\vec{B} = (3\hat{j} + 4\hat{k})\,T$. The induced $EMF$ in the rod is........$V$.

Identify from the following plant parts,the major contributors to human food?

Mass $M$ is divided into two parts $xM$ and $(1-x)M$. For a given separation,the value of $x$ for which the gravitational attraction between the two pieces becomes maximum is

An infinite number of electric charges each equal to $5 \text{ nC}$ (magnitude) are placed along the $X$-axis at $x=1 \text{ cm}, x=2 \text{ cm}, x=4 \text{ cm}, x=8 \text{ cm} \dots$ and so on. In this setup, if the consecutive charges have opposite signs, then the electric field in $\text{N/C}$ at $x=0$ is: $\left(\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 \text{ N} \cdot \text{m}^2/\text{C}^2\right)$