$A$ convex lens has its radii of curvature equal. The focal length of the lens is $f$. If it is divided vertically into two identical plano-convex lenses by cutting it,then the focal length of the plano-convex lens is ($\mu$ = the refractive index of the material of the lens).

Charge $q$ is uniformly distributed over a thin half ring of radius $R$. The electric field at the centre of the ring is

What is collagen?

$A$ horizontal pipe of non-uniform cross-section allows water to flow through it with a velocity $1 \ m/s$ when pressure is $50 \ kPa$ at a point. If the velocity of flow has to be $2 \ m/s$ at some other point,the pressure at that point should be (in $kPa$)

The points in the set $\{z \in \mathbb{C} : \arg \left(\frac{z-2}{z-6i}\right) = \frac{\pi}{2}\}$ (where $\mathbb{C}$ denotes the set of all complex numbers) lie on the curve which is a

Which of the following statements are correct for alkali metal compounds?
$(i)$ Superoxides are paramagnetic in nature.
$(ii)$ The basic strengths of hydroxides increase down the group.
$(iii)$ The conductivity of chlorides in their aqueous solutions decreases down the group.
$(iv)$ The basic nature of carbonates in aqueous solutions is due to cationic hydrolysis.