The cork cambium, cork, and secondary cortex are collectively called $........$.

The major product of the following reaction is

Which one of the following ions has the same number of unpaired electrons as those present in $V^{3+}$ ion?

$A$ balloon is filled with $500 \ m^3$ of helium gas at $27^{\circ}C$ and $1 \ atm$ pressure. What will be the volume of helium at $3^{\circ}C$ and $0.5 \ atm$ pressure in $m^3$?

The major product of the following reaction is:

If two compounds have the same empirical formula but different molecular formula,they must have: