Chemistry NCERT Exemplar Solutions Class 12th Chapter Sixteen

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(b, c)

(a) CHCl₃  (chloroform) was used as an anaesthesia in surgery but now it is used in the production of the Freon refrigerant R-22.

(b) Iodoform (CFH₃) produces iodine on coming in contact with skin, so it is used as an antiseptic for wounds.

(c) Boric acid (IT₃BO₃) in dilute aqueous solution is a weak antiseptic for eyes. Thus, chemical messenger gives message to the all without entering the cell.

(d) Chlorine in the concentration of 0.2 of 0.4 ppm in aqueous solution and sulphur dioxide in very low concentrations, are disinfectants.

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(b, d) Table salt and cane sugar are used, as food preservatives while sodium hydrogen carbonate and benzoic acid are not used as food preservatives.

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(b, d) Receptor proteins are embedded in the cell membrane and their active sites project outside region of the cell membrane. Shape of the receptor changes during the attachment of messenger.

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(b) Artificial sweeteners are non-caloric substitutes for sugar. They are often intensely more sweet than sugar but do not enhance nutritional value of food. Vitamins and minerals are essential nutrients because they perform hundreds of roles in the body.

Amino acids will also enhance the nutritional value of food.

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(d) Sucralose is an artificial sweetening agent which is 600 times sweeter than sucrose and does not provide calories.

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(c) Inhibitors are chemical substances which tend to reduce the activity of a particular enzyme. Generally, a weak bond such as H-bonding, van there Waals interaction, etc. is formed between the enzyme and the inhibitor.

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(c) Drugs usually interact with biomolecules such as carbohydrates, lipids, proteins and nucleic acids. These are called drug targets. Vitamins are not a target molecule for drug function in body.

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(c) Polyethyleneglycols are used in the preparation of non-ionic detergents.

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(b) Liquid dishwashing detergents are non-ionic detergents.

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(c) Glycerol is added to shaving soap to prevent rapid drying while to enhance the leathering property of soap, a gum called rosin is added to them. It forms sodium rosinate which lathers well.