$AB$ crystallizes in a body-centred cubic lattice with edge length '$a$' equal to $387 \ pm$. The distance between two oppositely charged ions in the lattice is ............. $pm$.

The angle between the lines whose direction cosines are given by the equations $l^2+m^2-n^2=0$ and $l+m+n=0$ is

Identify the plant shown in the given figure.

What is the percentage of Photosynthetically Active Radiation $(PAR)$ in the incident solar radiation?

Stokes' law states that the viscous drag force $F$ experienced by a sphere of radius $a$,moving with a speed $v$ through a fluid with coefficient of viscosity $\eta$,is given by $F=6 \pi \eta a v$. If this fluid is flowing through a cylindrical pipe of radius $r$,length $l$ and a pressure difference of $p$ across its two ends,then the volume of water $V$ which flows through the pipe in time $t$ can be written as $\frac{V}{t}=k\left(\frac{p}{l}\right)^a \eta^b r^c$,where $k$ is a dimensionless constant. The correct values of $a, b$ and $c$ are

The potential difference between $A$ and $B$ in the figure is .............. $V$.