In which aspect does the $Pulmonary \text{ } Artery$ differ from the $Pulmonary \text{ } Vein$?

$A$ conductor of length $1.5 \ m$ and area of cross-section $3 \times 10^{-5} \ m^2$ has an electrical resistance of $15 \ \Omega$. The current density in the conductor for an electric field of $21 \ Vm^{-1}$ is

Which proteinaceous pigment controls light-dependent activities in plants?

$\sqrt{2+\sqrt{5}-\sqrt{6-3 \sqrt{5}+\sqrt{14-6 \sqrt{5}}}}$ is equal to

If $|a|=4, |b|=5, |a-b|=3$ and $\theta$ is the angle between the vectors $a$ and $b$, then $\tan^2 \theta=$

$A$ person moves $30\, m$ north and then $20\, m$ towards east and finally $30\sqrt{2}\, m$ in south-west direction. The displacement of the person from the origin will be