Which tissue provides mechanical support to the young stem and petiole of leaves?

Which of the following compounds can form a zwitterion?

As per the Bohr model, the minimum energy (in $eV$) required to remove an electron from the ground state of a doubly ionized $Li$ atom $(Z=3)$ is:

In $\Delta ABC,$ if $\cos A + \cos C = 4\sin^2\frac{B}{2},$ then $a, b, c$ are in

For a first order reaction,the concentration of reactant was reduced from $0.03 \ mol \ L^{-1}$ to $0.02 \ mol \ L^{-1}$ in $25 \ min$. What is its rate (in $mol \ L^{-1} \ s^{-1}$)?

Which one of the following is most acidic?