Which structure in the embryo is considered the precursor to the urinary bladder?

Which kingdom includes unicellular or multicellular eukaryotic organisms?

$A$ magnetic needle lying parallel to a magnetic field is turned through $60^{\circ}$. The work done on it is $W$. The torque required to maintain the magnetic needle in the position mentioned above is

If $x_n = \cos \frac{\pi}{2^n} + i \sin \frac{\pi}{2^n}$,then $\prod_{n=1}^{\infty} x_n$ is equal to

The quantum numbers $+1/2$ and $-1/2$ for the electron spin represent

The number of normals drawn to the parabola $y^2 = 4x$ from the point $(1, 0)$ is