Question

The quantum yield for decomposition of HI is 0.2.In an experiment 0.01 moles are decomposed. The number of photons absorbed are:

• A. $3\times {10}^{22}$
• B. $6\times {10}^{22}$
• C. $8\times {10}^{22}$
• D. $4\times {10}^{22}$

Answer 1

Answer: (A)

$3\times {10}^{22}$

As per Avogadro hypothesis ,

1 mole $HI$ = $6.023\times {10}^{23}$ numbers of $HI$ molecules

$0.01$ mole $HI$= $6.023\times {10}^{21}$ numbers of $HI$ molecules

Quantum yield is defined as

Quantum yield = Molecules decomposed / photon absorbed

photon absorbed = Molecules decomposed /Quantum yield

$=\frac{6.023\times {10}^{21}}{0.2}=3.0115\times {10}^{22}$

Hence, the correct option is $A$