Question

Methylene blue, from its aqueous solution, is adsorbed on activated charcoal at 25°C. For this process, the correct statement is

[IIT-JEE-Advanced 2013]

• A. The adsorption required activation at 25°C
• B. The adsorption is accompanied by a decrease in enthalphy
• C. The adsorption increases with increase of temperature
• D. The adsorption is irreversible

Answer 1

The correct option is B

The adsorption is accompanied by a decrease in enthalphy

Adsorption of methylene blue on activated charcoal is physical adsorption hence it is characterized by decrease in enthalpy.

Hence (b) is correct.