(i) Why bithional is added in soap ?

(ii) Why magnesium hydroxide is a better antacid than sodium bicarbonate ?

(iii) Why soaps are biodegradable whereas detergents are non-biodegradable ?

OR

Define the following terms with a suitable example in each :

(i) Antibiotics

(ii) Artificial sweeteners

(iii) Analgesics

(i) To keep soap protected from bacteria, bithional is added to soap. Bithional is an antibacterial agent and can fight against bacteria.

(ii) The pH of sodium bicarbonate is near 8.25, which is quite alkaline. If NaHCO₃ is used then being soluble, it makes the stomach alkaline and triggers even more production of acid. On the other hand, Mg(OH)₂ is insoluble, and therefore, the pH remain neutral. Hence, Mg(OH)2 is a better antacid then NaHCO_3.

(iii) Soaps are sodium or potassium salts of fatty acids. Fats and oils can easily be broken down into simple molecules by microbes, and hence soaps are biodegradable. Detergents are synthetic compounds, generally ammonium or sulfonate salts of long chain carboxylic acids. These synthetic compounds cannot be broken down into simple molecules by microbes, and hence detergents are non-biodegradable.

OR

(i) Antibiotics are drugs to treat bacterial infections. These inhibit the growth of bacteria by blocking the biochemical pathways essential for their survival like protein synthesis. Eg. Tetracyclin, Penicillin.

(ii) Artificial sweetners are the synthetically prepared sweetners that are comparable in its sweetness with sugar. These are added to food items because these provides sweetness to food without adding much calories like sugar. Eg. Aspartame, Saccharin.

(iii) Analgesics are the medicines that has tendency to reduce pain without the loss of consciousness. Analgesics are commonly called pain-killers. Eg. Paracetamol