Question

Which of the following statement(s) are wrong?

• A. Photons having energy $400\text{kJ}$ will break 4 mole bonds of a molecule $A_2$ where $A-A$ bond dissociation energy is $100\text{kJ/mol}$
• B. Two bulbs are emitting light having wavelength $2000\stackrel{\circ }{A}$ and $3000\stackrel{\circ }{A}$ respectively. If the bulbs $A$ and $B$ are 40 watt and 30 watt respectively then the ratio of no. of photons emitted by $A$ and $B$ per day is $1:2$
• C. When an electron makes transition from lower to higher orbit, photon is emitted
• D. None of the above

Answer 1

Answer: (A), (B), (C)

When an electron makes transition from lower to higher orbit, photon is emitted

(A) Since the number of photons is not specified (it may or may not be equal to $4N_A$). So, this statement is not always true.
(B) No. of photon emitted per day $\times$ Energy of one photon = Energy emitted per day.
For bulb $A,n_{e_A}\times \frac{12400}{2000}\times 1.6\times {10}^{-19}=40\times 24\times 3600$
For bulb $B,n_{e_B}\times \frac{12400}{3000}\times 1.6\times {10}^{-19}=30\times 24\times 3600$
$\therefore n_{e_A}:n_{e_B}=8:9$
(C) When an electron makes transition from lower to higher orbit, a photon is absorbed.