Question

A one litre flask is full of brown bromine vapours. The intensity of brown colour of vapours will not decrease appreciably on adding to the flask some

• A. pieces of marble
• B. animal charcoal powder
• C. carbon tetrachloride
• D. ) carbon disulphide

Answer 1

The Correct Option is A

 To understand why the intensity of the brown bromine vapours will not decrease appreciably on adding pieces of marble to the flask, we must consider the chemical properties of bromine and its interactions with various substances given in the options.

1. Bromine is a non-metal and it exists as diatomic molecules in its vapor form, appearing as brown vapors.
2. Let's analyze the provided options:
   • Pieces of Marble: Marble is primarily composed of calcium carbonate (CaCO₃). Bromine generally does not react with calcium carbonate under normal conditions as there is no chemical affinity between them. Therefore, adding pieces of marble to the flask will not influence the concentration or intensity of bromine vapors significantly.
   • Animal Charcoal Powder: Animal charcoal is known for its adsorption properties. It can adsorb bromine vapors from the air, decreasing their concentration. Therefore, adding animal charcoal would decrease the intensity of the bromine vapours.
   • Carbon Tetrachloride: Carbon tetrachloride (CCl₄) is a non-polar solvent where bromine can dissolve, leading to a probable reduction in vapour density as more bromine dissolves in the solvent. This would decrease the intensity of bromine vapors.
   • Carbon Disulphide: Like carbon tetrachloride, carbon disulphide (CS₂) is also a non-polar solvent. It is known to dissolve bromine very effectively, which would decrease the vapor concentration and hence the intensity of its color.
3. Based on the above analysis, the only substance among the options that does not cause a significant decrease in the intensity of bromine vapors is pieces of marble.

Therefore, the correct answer is pieces of marble.