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

Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.

Excess ethanol and acid

Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN)

How will you bring about the following conversion in not more than two steps?

Bromobenzene to 1-Phenylethanol

Give plausible explanation for the following:

Cyclohexanone forms cyanohydrin in good yield but 2, 2, 6 trimethylcyclohexanone does not.

Give plausible explanation for the following:

There are two −NH₂ groups in semicarbazide. However, only one is involved in the formation of semicarbazones.

Complete the synthesis by giving missing starting material, reagent or product.

\[\ce{C6H5CHO ->[H2NCONHNH2]}\]

Complete the synthesis by giving missing starting material, reagent or product.

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)