Question

Assertion (A): A mixture of acetylene and air is used for welding because burning of acetylene in air produces a blue flame (due to complete combustion) which is hot enough to melt metals for welding.

Reason (R): Iodine tincture is an antiseptic solution. It is a solution of iodine in ethanol. Iodine is the real germ killer. Ethanol acts as a solvent to dissolve iodine. This is because iodine is not much soluble in water.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

A is false but R is true.

Explanation:

The Assertion is false because acetylene heated in air undergoes incomplete combustion due to limited oxygen, producing a smoky, yellow soot flame that is not hot enough for welding. Instead, a mixture of acetylene and pure oxygen (oxy-acetylene) is required to produce the hot blue flame that melts metals. The Reason is a completely true, independent statement that accurately describes the tincture of iodine.