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

Write the name of the reagent and equation for the preparation of the following ethers by Williamson’s synthesis:

1-Methoxyethane

Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.

How is 1-propoxypropane synthesised from propan-1-ol? Write mechanism of this reaction.

Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reason.

Explain the following with an example.

Williamson ether synthesis

How the following conversion can be carried out?

Benzene to 4-bromonitrobenzene

Complete the following reactions: C₂H₄ + O₂ →

Complete the following reactions:  4Al + 3O₂ →

Why is dioxygen a gas but sulphur a solid?

Why do noble gases have comparatively large atomic sizes?

Write the structure of 3-Bromo-2-methylprop-1-ene

Give reasons  Acetylation of aniline reduces its activation effect.

Out of PbS and PbCO₃ (ores of lead), which one is concentrated by froth floatation process preferably?

Write the hybridisation and magnetic character of [Co(C₂O₄)₃]^3–.

(At. no. of Co = 27)

After watching a programme on TV about the presence of carcinogens (cancer causing agents) Potassium bromate and Potassium iodate in bread and other bakery products, Ritu a class XII student decided to aware others about the adverse effects of these carcinogens in foods. She consultanted the school principal and requested him to instruct canteen contractor to stop selling sandwiches, pizza, burgers and other bakery products to the students. Principal took an immediate action and instructed the canteen contractor to replace the bakery products with some proteins and vitamins rich food like fruits, salads, sprouts etc. The decision was welcomed by the parents and students.

After reading the above passage, answer the following questions:

1) What are the values (at least two) displayed by Ritu?

2) Which polysaccharide component of carbohydrates is commonly present in bread?

3) Write the two types of secondary structure of proteins.

4) Give two examples of water soluble vitamins.

Why is [NiCl₄]²⁻ paramagnetic while [Ni(CN)⁴]²⁻ is diamagnetic? (Atomic number of Ni = 28)

Write one difference in Coagulation and Peptization

CO (g) and H₂ (g) react to give different products in the presence of different catalysts. Which ability of the catalyst is shown by these reactions?

Write the hybridization type and magnetic behaviour of the complex [Ni(CN)₄]²⁻. (Atomic number of Ni = 28)

Indicate the principle behind the method used for the refining of Nickel.