Which of the following is an allotropic form of carbon used in lead pencils? MCQ with Answer and Explanation

Explanation:
Ideal gas assumptions: particles have negligible volume, no intermolecular forces, and elastic collisions. Real gases deviate due to finite molecular size and attractions. At high pressure and low temperature, real gases deviate significantly; van der Waals equation corrects. So having strong attractive forces is not an ideal gas property. Ideal gas law PV = nRT is a limiting law.

Explanation:
In electrolytic refining of copper, impure copper is used as the anode, a thin sheet of pure copper as the cathode, and CuSO₄ acidified with H₂SO₄ as electrolyte. On passing current, copper dissolves from the anode and pure copper deposits on the cathode. Impurities like gold, silver fall as anode mud. This yields 99.99% pure copper. Similar process for other metals.

Explanation:
Distillation separates liquids based on their different boiling points. The mixture is heated; the component with lower boiling point vaporizes first, is condensed and collected. Fractional distillation is used for smaller boiling point differences. Filtration separates solids from liquids. Sublimation separates sublimable solids. Magnetic separates magnetic substances.