If $a$₀ is denoted as the Bohr radius of hydrogen atom, then what is the de-Broglie wavelength (λ) of the electron present in the second orbit of hydrogen atom? [n : any integer]

Which of the following is/are not correct with respect to energy of atomic orbitals of hydrogen atom?

(A) 1s < 2p < 3d < 4s

(B) 1s < 2s = 2p < 3s = 3p

(C) 1s < 2s < 2p < 3s < 3p

(D) 1s < 2s < 4s < 3d

Choose the correct answer from the options given below :

In a multielectron atom, which of the following orbitals described by three quantum numbers will have same energy in absence of electric and magnetic fields?

A. $\mathrm{n}=1, \mathrm{l}=0, \mathrm{~m}_1=0$

B. $\mathrm{n}=2, \mathrm{l}=0, \mathrm{~m}_1=0$

C. $\mathrm{n}=2, \mathrm{I}=1, \mathrm{~m}_1=1$

D. $\mathrm{n}=3, \mathrm{l}=2, \mathrm{~m}_1=1$

E. $\mathrm{n}=3, \mathrm{l}=2, \mathrm{~m}_1=0$

Choose the correct answer from the options given below:

For hydrogen atom, the orbital/s with lowest energy is/are :

(A) $\mathrm{4 s}$

(B) $3 \mathrm{p}_x$

(C) $3 \mathrm{~d}_{x^2-y^2}$

(D) $3 \mathrm{~d}_{z^2}$

(E) $4 \mathrm{p}_z$

Choose the correct answer from the options given below :