Science (English Medium) Class 12 - CBSE Important Questions for Chemistry

Draw the structure of the following molecule: 

XeF₄

Define terms: Fuel cell

Write the equation involved in the following reaction:

Reimer-Tiemann reaction

How do you convert the Toluene to Benzoic acid

Write the chemical equation involved in the following reaction:

Hoffmann-bromamide degradation reaction

Illustrate the following reaction giving suitable example in each case:Gabriel phthalimide synthesis

Amino acids show amphoteric behaviour. Why?

A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction. (Given : log 2 = 0·3010, log 4 = 0·6021, R = 8·314 JK^–1 mol^–1)

Draw the structures of the HClO₃.

Propanal and Propanone

Write the chemical equations to illustrate the following name reaction: 

Cannizzaro’s reaction

Give reasons for the following:

Aniline does not undergo Friedel- Crafts reaction.

Define the following terms: Essential amino acids

Why is bithional added to soap?

Calculate the freezing point of a solution containing 60 g of glucose (Molar mass = 180 g mol^–1) in 250 g of water. (K_f of water = 1.86 K kg mol^–1)

Give reasons for the following:

Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.

Give reasons for the following :

Aquatic animals are more comfortable in the cold water than in warm water.

Give reasons for the following

Elevation of the boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.

An element 'X' (At. mass = 40 g mol^-1) having f.c.c. the structure has unit cell edge length of 400 pm. Calculate the density of 'X' and the number of unit cells in 4 g of 'X'. (N_A = 6.022 × 10²³ mol^-1)

Write the cell reaction and calculate the e.m.f of the following cell at 298 K:

`Sn(s) | Sn^(2+) (0.004 M) || H^(+) (0.020 M) | H_2 (g) ("1 bar") | Pt(s)`

(Given: `E_(Sn^(2+)"/"Sn)^0 = -0.14` V)