Question

When the number of molecules decomposed is less than one per photon, the reaction has ______ quantum yield.

(a) low

(b) high

(c) unpredictable

(d) variable

I have been asked this question in an international level competition.

My enquiry is from Quantum Efficiency topic in section Photochemistry of Engineering Chemistry I

Answer 1

The correct choice is (a) low

The explanation: When the number of molecules decomposed is less than one per photon, the reaction has less than one quantum yield. So, the reaction has low quantum yield.

Quantum efficiency=Number of molecules reacting in a given time/Number of quanta of light absorbed in the same time.