Chemistry MCQs for NEET — Practice Questions with Answers

Distillation is the method used to separate a mixture of acetone and ethanol because they have different boiling points. Acetone boils at around 56°C, whereas ethanol boils at around 78°C. By heating the mixture, acetone will vaporize first, allowing it to be condensed and collected separately from ethanol.

Sublimation is the suitable technique for separating a mixture of calcium sulphate and camphor because camphor can sublimate (change directly from solid to gas) upon heating, while calcium sulphate does not. This property allows camphor to be separated from calcium sulphate effectively.

Steam distillation is the appropriate method for extracting essential oils from flowers. Essential oils are steam volatile and can be distilled along with water vapor, which allows them to be separated from the non-volatile organic compounds present in the flowers.

Kjeldahl’s method cannot be used for the estimation of nitrogen in DNA and RNA because these molecules contain nitrogen in heterocyclic rings, which do not break down under the conditions of the Kjeldahl method.

Iodine can be separated from sodium chloride using the method of sublimation. Sublimation is the process where a solid changes directly to a gas without passing through the liquid state. Iodine is a substance that can sublime, while sodium chloride does not. Hence, when the mixture is heated, iodine will turn into vapor and can be collected after cooling, leaving behind sodium chloride.

The formula for iron (III) hexacyanoferrate (II) is $ Fe_4[Fe(CN)_6]_3 $. In this compound, iron exists in two oxidation states: Fe(III) and Fe(II). The hexacyanoferrate (II) ion is $ [Fe(CN)_6]^{4-} $, and when combined with Fe(III) ions, the overall formula becomes $ Fe_4[Fe(CN)_6]_3 $.

Fractional distillation is used to separate mixtures of liquids with different boiling points. Since the boiling points of liquids A and B differ by 15K, fractional distillation is the appropriate method for their separation. This method utilizes a fractionating column to separate the components based on their boiling points.

Solvent extraction is used to separate an organic compound from its aqueous solution. This process involves transferring a solute from one solvent into another based on the differing solubilities of the solute in the two solvents, making it an effective method for separation.