Question

Statement I: The angular momentum of an electron in the third orbit of singly ionized helium atom is same as in the third orbit of hydrogen atom or third orbit of doubly ionized Lithium atom.

Statement II: The angular momentum of an electron in Bohr's atomic model is independent of the no of protons in the nucleus and is quantized.

Which of the options are correct?

• A. Statement I is true, Statement II is true and statement II is a correct explanation of Statement I.
• B. Statement I is true, Statement II is true but Statement II is not a correct explanation of statement I
• C. Statement I is false but statement II is true.
• D. Statement I is true but statement II is false.

Answer 1

The correct option is A Statement I is true, Statement II is true and statement II is a correct explanation of Statement I.

The angular momentum of an electron in an atom is quantized and is given by
$L=\frac{nh}{2\pi }$ (Where n is the no of orbit, electron is at).
We observe, the expression is independent of Z (no. of protons in the nucleus)
Now, for the nth orbit of hydrogen $L=\frac{nh}{2\pi }.$
For the nth orbit of singly ionized helium $L=\frac{nh}{2\pi }.$
Or, for the nth orbit of doubly ionized lithium $L=\frac{nh}{2\pi }.$
So, as long as we talk about the same no of orbit, the angular momentum will be same be it for any hydrogen like atom, irrespective of the value of Z.