CBSE Class 12th Chemistry Solved Question Paper 2013 Set-1

Some solved questions from CBSE Class 12th Chemistry Solved Question Paper (Set-1) are given here

Q. Of physisorption or chemisorption, which has a higher enthalpy of adsorption?

Answer. Chemisorption has a higher enthalpy of adsorption.

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Q. Name the method used for refining or copper metal.

Answer. Electrolytic method is used for refining of copper metal.

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Q. What are the products of hydrolysis of sugar?

Answer. Sucrose & Glucose

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Q. Account for the following:

(i) Schottky defects lower the density of related solids.

(ii) Conductivity of silicon increases on doping it with phosphorus.

Answer.

(i) Schottky defect is a vacancy defect which is shown by ionic solids. In this defect, an equal number of cations and anions are missing from their sites to maintain electrical neutrality. This leads to decrease in the density of a substance.

(ii) Silicon contains four valence electrons in its valence shell. When doped with phosphorus which is a group 15 element. Phosphorus contains five valence electrons which occupy some of the lattice sites in silicon. Four out of five electrons are used in the formation of four covalent bonds with the four silicon atoms. The fifth electron is extra and becomes delocalised. These delocalised electrons increase the conductivity of doped silicon

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Q.

(a) Name the method used for removing gangue from sulphide ores

(b) How is wrought iron different from steel?

Answer.

(a) Froth floatation method

(b) Wrought Iron is the purest form of iron & is prepared from cast iron. On the other hand, Steel is an alloy of iron. Steel possesses greater tensile strength than wrought iron.

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