Given below are two statements.
Statement I : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in positive charges on the nucleus as there is no strong hold on the electron by the nucleus.
Statement II : According to Bohr's model of an atom, qualitatively the magnitude of velocity of electron increases with decrease in principal quantum number.
In the light of the above statements, choose the most appropriate answer from the options given below :

Solution

Chemistry ma’am · 4 steps

Write v ∝ Z/n first, then read each statement against it. Fewer protons means a slower electron.

1. Bohr's velocity. In Bohr's model, the speed of an electron in the nth orbit of an atom or ion with nuclear charge Z is fixed by Z and n alone.

   vₙ = 2.18 × 10⁶ × Z/n m s⁻¹

2. Statement I. v is directly proportional to Z, so less positive charge on the nucleus gives a smaller velocity. A weaker pull is exactly why the electron moves slower, so Statement I is false.
3. Statement II. v is inversely proportional to n, so a smaller principal quantum number gives a larger velocity. For hydrogen, v₁ is twice v₂. Statement II is true.
4. So. Statement I is false and Statement II is true, which is option (c).

The idea to keep. In Bohr's model v ∝ Z/n: a stronger nucleus or an inner orbit means a faster electron. Never let "weaker hold" trick you into "faster".

Answer from the NTA final answer key. Solution by PrepWiser.