Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

A primary amine, \[\ce{RNH2}\] can be reacted with \[\ce{CH3-X}\] to get secondary amine, \[\ce{R-NHCH3}\] but the only disadvantage is that 3° amine and quaternary ammonium salts are also obtained as side products. Can you suggest a method where \[\ce{RNH2}\] forms only 2° amine?

Assertion: Acetanilide is less basic than aniline.

Reason: Acetylation of aniline results in decrease of electron density on nitrogen.

Identify the type of polymer.

—A—B—B—A—A—A—B—A—

Which of the following chemicals can be added for sweetening of food items at cooking temperature and does not provide calories?

Which of the following will not enhance nutritional value of food?

Which of the following are not used as food preservatives?

(i) Table salt

(ii) Sodium hydrogencarbonate

(iii) Cane sugar

(iv) Benzoic acid

Sugar is the main source of energy as it produces energy on metabolic decomposition. But these days low calorie drinks are more popular, why?

Pickles have a long shelf life and do not get spoiled for months, why?

What is the difference between saccharin and saccharic acid?

Name an artificial sweetener which is derivative of sucrose.

Name two α-amino acids which form a dipeptide which is 100 times more sweet than cane sugar?

Aspartame is unstable at cooking temperature, where would you suggest aspartame to be used for sweetening?

Sodium salts of some acids are very useful as food preservatives. Suggest a few such acids.

Assertion: All chemicals added to food items are called food preservatives.

Reason: All these chemicals increase the nutritive value of the food.

Assertion: Preservative are added to food items.

Reason: Preservatives inhibit the growth of microorganisms.

Assertion: Artificial sweeteners are added to the food to control the intake of calories.

Reason: Most of the artificial sweeteners are inert and do not metabolise in the body.

\[\ce{H2}\] gas is adsorbed on activated charcoal to a very little extent in comparison to easily liquefiable gases due to:

(i) very strong van der Waal’s interaction.

(ii) very weak van der Waals forces.

(iii) very low critical temperature.

(iv) very high critical temperature.

Give reasons to support the answer:

Presence of Alpha hydrogen in aldehydes and ketones is essential for aldol condensation.

In a coordination entity, the electronic configuration of the central metal ion is t_2g³ e_g¹

Is the coordination compound a high spin or low spin complex?

What happens when reaction:

Aniline reacts with chloroform in the presence of alcoholic potassium hydroxide