Question

Caesium is used in

• A. devising photoelectric cells
• B. air conditioning plants
• C. extraction of boron
• D. fast breeder nuclear reactors

Hint:

Alkali metals with low ionisation energy show strong photoelectric effect.

Answer 1

The Correct Option is A

Step 1: Property of caesium.
Caesium has very low ionisation energy and easily emits electrons when exposed to light.
Step 2: Application based on property.
Due to its high photoelectric sensitivity, caesium is used in photoelectric cells.
Step 3: Eliminate other options.
Air conditioning uses refrigerants, boron extraction uses magnesium, and fast breeder reactors use liquid sodium.
Step 4: Conclusion.
Hence, caesium is used in devising photoelectric cells.