Question

Given below are two statements Statement-I: Silicones have high thermal stability and high dielectric strength Statement-II: In silica Si-O bond enthalpy is very high

• A. Both statements I and II are correct
• B. Both statements I and II are not correct
• C. Statement I is correct, but statement II is not correct
• D. Statement I is not correct, but statement II is correct

Hint:

Silicone properties originate from strong Si-O bond. Stronger bond means higher thermal stability and excellent insulating behavior.

Answer 1

The Correct Option is A

Step 1: Recall what silicones are.
Silicones are organosilicon polymers built on a silicon-oxygen backbone, $(-\text{Si}-\text{O}-\text{Si}-\text{O}-)_n$.
Step 2: Examine statement I.
Silicones are known for high thermal stability, water resistance, chemical inertness, and high dielectric strength, the last meaning excellent electrical insulation. So statement I is true.
Step 3: Recall the Si-O bond strength.
The silicon-oxygen bond enthalpy is very large, about 452 kJ per mol, much stronger than ordinary single bonds.
Step 4: Examine statement II.
In silica this strong Si-O bond gives the network great stability, so statement II is true.
Step 5: Link the two.
The strong Si-O bond is exactly why silicones resist thermal breakdown, so statement II explains statement I.
Step 6: Conclude.
Both statements are correct, which is option 1.
\[ \boxed{\text{Both statements I and II are correct}} \]