Central Board of Secondary Education Class 12th Science past year question papers

Will you please share with me the Central Board of Secondary Education Class 12th Science past year question papers?

[Quick Sam]

As you want to get the Central Board of Secondary Education Class 12th Science past year question papers so here it is for you:

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List of subjects of Central Board of Secondary Education Class 12th Science:
Physics
Chemistry
Mathematics
English
Biology

Here for your reference I am giving you the papers of English:

Some content of the file has been given here:

Central Board of Secondary Education Class 12th English papers










Contact Details:
Central Board of Secondary Education
Community Centre,
Preet Vihar Metro Railway Station,
Shiksha Kendra,Building No.2,
Acharya Nag Raj Marg,
Block D, Preet Vihar,
New Delhi,
Delhi 110092 ‎
011 2202 3737 ‎
India

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I want to score well in class 12th board, please forward me CBSE class 12th chemistry previous year papers?

[Kiran Chandar]

As per your request, I am giving you question paper of the chemistry of CBSE class 12th with solutions.

Q. What are the products of hydrolysis of sucrose?

Sol. Hydrolysis of sucrose gives glucose and fructose.

Q. State Kohlrausch's law of independent migration of ions. Why does the conductivity of a solution decrease with dilution?

Sol. Kohlrausch's law of independent migration of ions states that the limiting molar conductivity of an electrolyte can be represented as the sum individual contributions of its cations & anions.

Conductivity of a solution decreases with dilution as with dilution number of ions per unit volume decreases.

Q. What is the effect of temperature on chemisorption?

Sol. Chemisorption increases with increase in temperature.

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

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

Q. What are the products of hydrolysis of sugar?

Answer. Sucrose & Glucose

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

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.

For complete questions, consider the attachment.

CBSE class 12th chemistry paper