Question

Given below are two statements:
Statement (I): 2:1 layer silicates consist of two tetrahedral sheets bound to either side of an octahedral sheet
Statement (II): Two tetrahedral sheets of 2:1 layer silicates is bound to one side of an octahedral sheet in 2:1 layer silicates

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

2:1 clays always follow tetrahedral-octahedral-tetrahedral arrangement.

Answer 1

The Correct Option is C

In 2:1 clay minerals like montmorillonite, two tetrahedral sheets sandwich an octahedral sheet. Statement I is accurate. Statement II wrongly states the configuration.

Answer 2

Structural-diagram reasoning: Picture the octahedral sheet as the middle layer of a three-layer sandwich. In a true 2:1 layer silicate (e.g., montmorillonite, illite, vermiculite), a tetrahedral sheet is fused to the top face of the octahedral sheet AND a second tetrahedral sheet is fused to the bottom face, so the octahedral sheet is sandwiched on both sides. This matches Statement (I), which is therefore correct.
Statement (II) instead describes both tetrahedral sheets being attached to only one side of the octahedral sheet, which would leave the other face exposed, that is not how a 2:1 mineral is built (it resembles neither a 1:1 nor a 2:1 structure correctly), so Statement (II) is incorrect.