Assertion : A radiation of wavelength `1216 Å` is emitted when an hydrogen atom goes from its first excited state back to the ground state.
Reason : Minimum energy required to excite an hydrogen atom from n=1 to n=2 state is 10.2 eV.

Options

A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If both Assertion and Reason are false.

Explanation

Energy of electron in ground state is -13.6 eV.
Energy of electron in n=2 state is -3.4eV.
Therefore, an energy of 10.2eV will excite the electron from the ground state to the Ist excited state i.e. to the next higher level n=2.
When the electron jumps back to the ground state it emits the same amount of energy in the form of electromagnetic waves. The wavelength of the emitted radiation is
`(1)/(lamda ) = v/c = (E)/( hc ) implies lamda = (hc)/(E) = (6.6 xx 10 ^(-34) xx 3 xx 10 ^(8))/(10.2 xx 1 . 6 xx 10 ^(-19))`
`=1.216 xx 10 ^(-7) m = 1216 Å`