Q14 / 75 · JEE Main 2026 (21 January Shift 1) · Chemistry

Given below are two statements :
Statement I: When an electric discharge is passed through gaseous hydrogen, the hydrogen molecules dissociate and the energetically excited hydrogen atoms produce electromagnetic radiation of discrete frequencies.
Statement II: The frequency of second line of Balmer series obtained from $\mathrm{He}^{+}$is equal to that of first line of Lyman series obtained from hydrogen atom.
In the light of the above statements, choose the correct answer from the options given below :

  • A
    Statement I is false but Statement II is true
  • Correct answer
    B
    Both Statement I and Statement II are true
  • C
    Statement I is true but Statement II is false
  • D
    Both Statement I and Statement II are false

Solution

Statement I: Electric discharge through $H_2$ causes dissociation into excited H atoms which emit discrete frequencies (line spectrum). This is true.
Statement II: Using $\nu = RcZ^2\left(\frac{1}{n_1^2} - \frac{1}{n_2^2}\right)$
For $He^+$ (Z=2), second Balmer line ($n_1=2, n_2=4$): $\nu = 4Rc\left(\frac{1}{4} - \frac{1}{16}\right) = \frac{3Rc}{4}$
For H (Z=1), first Lyman line ($n_1=1, n_2=2$): $\nu = Rc\left(1 - \frac{1}{4}\right) = \frac{3Rc}{4}$
Both frequencies are equal. Statement II is true.
Both statements are true.

Hence, the correct answer is option: 'B'.

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