Chemistry MCQs for NEET — Practice Questions with Answers

For effective crystallization, the solvent should exhibit two main properties: the impure compound should be sparingly soluble in it at room temperature and appreciably soluble at higher temperatures. This ensures that upon cooling, the pure compound crystallizes out, leaving impurities in the solution.

Distillation is useful for separating liquids with a significant difference in their boiling points. This method relies on heating the mixture to vaporize the more volatile component, which is then condensed back into a liquid in a separate container.

200ml of compound = 1 gm $ \therefore $ 22400 ml of compound = 112 gm

To separate a mixture of chloroform (b.p 334K) and aniline (b.p 457K), distillation can be used. The substantial difference in boiling points allows for effective separation by selectively boiling and condensing each component.

To find the minimum molecular weight of insulin, we use the percentage of sulfur present. Given that insulin contains 3.4% sulfur, we assume the presence of one sulfur atom in the smallest unit of insulin. The atomic weight of sulfur is approximately 32 g/mol. Let's denote the minimum molecular weight of insulin as M. The percentage of sulfur can be expressed as (32/M) * 100% = 3.4%. Solving for M, we have M = (32 * 100) / 3.4 = 941.18. Since 941.18 is closest to option 940, the minimum molecular weight of insulin is approximately 940.

The Carius method is used for the quantitative determination of halogens (chlorine, bromine, and iodine), sulfur, and phosphorus in organic compounds. The organic compound is heated with fuming nitric acid in a sealed tube, resulting in the formation of silver halide (if halogens are present) which can be weighted. Therefore, the element estimated by the Carius method is Halogen.

Distillation under reduced pressure is used when a liquid has a very high boiling point and decomposes at or below its boiling point. The reduced pressure lowers the boiling point of the liquid, allowing it to be distilled without decomposition.