Identify the correct statements from the following:
A. Heisenberg uncertainty principle is applicable to electrons.
B. The size of $$2p_x$$ orbital is less than the size of $$3p_x$$ orbital.
C. The energy of 2s orbital of H atom is equal to the energy of 2s orbital of Li.
D. The electronic configuration of Cr is [Ar] $$3d^5 4s^1$$
Choose the correct answer from the options given below:

Statement A: Heisenberg uncertainty principle is applicable to electrons.

Correct,

The Heisenberg uncertainty principle applies to microscopic particles like electrons.

Statement B: The size of $$2p_x$$ orbital is less than the size of $$3p_x$$ orbital.

Correct,

Sizes of Orbitals increases with increase in Principal Quantum Number $$(n)$$

so, 

$$3p_x>2p_x$$

Statement C: The energy of $$2s$$ orbital of $$H$$ atom is equal to the energy of $$2s$$ orbital of $$Li$$.

Incorrect,

In hydrogen-like atoms, energy depends mainly on $$n$$, but in multi-electron atoms like lithium, electron-electron interactions change orbital energies.

So, $$2s$$ of $$H$$ and $$2s$$ of $$Li$$ don't have same energy.

Statement D: The electronic configuration of Cr is [Ar] $$3d^5 4s^1$$.

Correct,

Chromium shows higher stability due to half-filled $$3d^5$$ configuration.

Therefore, Option B is correct.