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

The roots of the equation $x^3-14x^2+56x-64=0$ are in

If $\theta$ is the angle between the lines $x^2+2 h x y+b y^2=0$,then the angle between $x^2+2 x y \sec \theta+y^2=0$ is

$11^2 + 12^2 + 13^2 + \dots + 20^2 = ?$

Two capillary tubes of same diameter are put vertically one each in two liquids whose relative densities are $0.8$ and $0.6$ and surface tensions are $60$ and $50 \, dyne/cm$ respectively. The ratio of the heights of the liquids in the two tubes $\frac{h_1}{h_2}$ is:

$Fe$ is made passive by