Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Chemistry

Give the equations of reactions for the preparation of phenol from cumene.

Write chemical reaction for the preparation of phenol from chlorobenzene.

You are given benzene, conc. H₂SO₄ and NaOH. Write the equations for the preparation of phenol using these reagents.

Write the equation for the preparation of 1-iodobutane from but-1-ene.

How will you bring about the following conversion?

Ethane to bromoethene

How the following conversion can be carried out?

Aniline to chlorobenzene

What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO₂?

Give reasons CH₃NH₂ is more basic than C₆H₅NH₂.

Following data are obtained for reaction :

N₂O₅ → 2NO₂ + 1/2O₂

1) Show that it follows first order reaction.

2) Calculate the half-life.

(Given log 2 = 0.3010, log 4 = 0.6021)

An element has atomic mass 93 g mol⁻¹ and density 11.5 g cm^–3. If the edge length of its unit cell is 300 pm, identify the type of unit cell. (N_A = 6.023 × 10²³ mol⁻¹)

Calculate the number of unit cells in 8.1 g of aluminium if it crystallizes in a f.c.c. structure. (Atomic mass of Al = 27 g mol^–1)

Give reason for the following:

Red phosphorus is less reactive than white phosphorus.

A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75% of the reaction will be completed.

(Given : log = 2 = 0·3010, log 3 = 0·4771, log 4 = 0·6021)

Give reasons for the following :

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

Write the chemical reactions involved in the process of extraction of Gold. Explain the role of dilute NaCN and Zn in this process.

Write the product when D-glucose reacts with conc. HNO₃.

Give reason (CH₃)₂NH is more basic than (CH₃)₃N in an aqueous 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)

 Arrange the following in the increasing order of their pK_b values:

C₆H₅NH₂, C₂H₅NH₂, C₆H₅NHCH₃

Which allotrope of sulphur is thermally stable at room temperature ?