Question

Given below are two statements : Statement I : Colourless cupric metaborate is reduced to cuprous metaborate in a luminous flame. Statement II : Cuprous metaborate is obtained by heating boric anhydride and copper sulphate in a non-luminous flame. In the light of the above statements, choose the most appropriate answer from the options given below.

• A. Statement I is true but Statement II is false
• B. Both Statement I and Statement II are false
• C. Statement I is false but Statement II is true
• D. Both Statement I and Statement II are true

Answer 1

The Correct Option is B

The given problem consists of two statements regarding chemical reactions involving copper metaborate and its transformation conditions. We need to determine the truthfulness of each statement.

1. Analyzing Statement I: "Colourless cupric metaborate is reduced to cuprous metaborate in a luminous flame."
   • Chemically, a luminous flame typically indicates incomplete combustion, resulting in a higher presence of carbon particles. Such a flame does not provide a suitable environment for reduction reactions involving metal oxides or metaborates because the presence of excess carbon and insufficient oxygen are unfavorable for specific reaction pathways.
   • Cupric (or copper(II)) compounds generally require an environment conducive to intense heat and minimum impurities for proper reduction to cuprous (or copper(I)) compounds. A non-luminous flame, which provides a hotter and cleaner environment due to complete combustion, is often more appropriate for reduction reactions.
   • Therefore, the statement that cupric metaborate is reduced in a luminous flame does not align with typical chemical behavior and is false.
2. Analyzing Statement II: "Cuprous metaborate is obtained by heating boric anhydride and copper sulphate in a non-luminous flame."
   • Boric anhydride (boron oxide) and copper sulphate don’t directly form cuprous metaborate upon heating. Typically, copper sulphate would decompose under heat to form copper oxide first, and further reactions may lead to the formation of cupric compounds rather than cuprous ones unless specific reduction agents are introduced.
   • The statement implies a formation process that doesn’t match chemical processes as understood for such compounds under typical conditions. Hence, this process does not typically lead to the formation of cuprous metaborate.
   • This makes Statement II false as well, under conventional chemical understanding.

In light of these analyses, the most appropriate answer is:

Both Statement I and Statement II are false.

This conclusion is consistent with conventional chemistry knowledge about metal compound transformation and specific flame conditions.