Answer: A) mercaptans Explanation: mercaptans (or thioalcohols) have a foul odour

Answer: C) nitrous acid Explanation: Nitrous acid act as an oxidising agent because it oxidises potassium iodide to iodine. It is also a reducing agent because it decolourises acidified potassium permanganate solution. Nitric acid acts only as an oxidising agent Ammonia acts only as a reducing agent Nitrogen peroxide acts only as an oxidising agent.

Answer: B) Silver nitrate Explanation: Silver nitrate is the basic substance from which silver bromide is obtained. The photographic films are impregnated with the light sensitive AgBr.

Answer: C) copper Explanation: In making jewels, gold is usually mixed with copper to make it little hard.

Answer: A) wrought iron Explanation: Wrought Iron is the purest form of iron. It contains 0.12 to 0.25% carbon and so it is the purest form of iron.

Answer: B) Electrophoresis Explanation: Dust particles such as coal dust(smoke) are fine particle of a solid (carbon in the case of smoke) dispersed in air. They are colloidal systems and the particles are charged either positive or negative. In an applied electrical field, they are attracted towards the opposite electrodes. Movement of the particles towards the electrodes is known as 'electrophoresis'. Hence electrophoresis is applied to remove smoke within the chimeny itself without allowing it to escape into the air and cause nuisance.

Answer: C) it gets oxidised to phosgene Explanation: Chloroform, CHCl3 is easily oxidised to the highly poisonous gas known as phosgene or carbonyl chloride COCl2. Hence if it is used as anaesthetic it should be kept free from sunlight and air.

Answer: A) acetone Explanation: Acute diabetes results in the formation of acetone in the body. Hence such patients smell of acetone.