Chemistry - Study Mode
[#341] Which of the following is used in making smoke bombs?
Correct Answer
(D) Carbon
Explanation
Solution: A smoke bomb is a firework designed to produce smoke upon ignition. Smoke bombs are useful to military units, airsoft games, paintball games, selfdefense and pranks. The smoke bomb was first created in 1848, by the inventor Robert Yale. He developed 17th century Chinese-style fireworks and later modified the formula to produce more smoke for a longer period of time. Coloured smoke devices use a formula that consists of an oxidizer (typically potassium chlorate, KClO 3 ), a fuel (generally sugar), a moderant (such as sodium bicarbonate) to keep the reaction from getting too hot, and a powdered organic dye. The burning of this mixture evaporates the dye and forces it out of the device, where it condenses in the atmosphere to form a “smoke” of finely dispersed particles. A smoke ball is a hollow, cherry-sized sphere of brightly coloured clay or cardboard filled with a smoke-generating composition that produces a forceful jet of coloured smoke for 10 to 15 seconds.
[#342] Water gas is the mixture of
Correct Answer
(C) Carbon monoxide and hydrogen
Explanation
Solution: Water gas is a mixture of carbon monoxide (CO) and hydrogen (H 2 ) produced by passing steam over red-hot coke using the endothermic reaction.
[#343] In electro-refining, the pure metal is deposited on
Correct Answer
(C) Cathode
Explanation
Solution: In electro-refining, the anodes consist of unrefined impure metal, and as the current passes through the acidic electrolyte the anodes are corroded into the solution so that the electroplating process deposits refined pure metal onto the cathodes. Electrolytic refining is used to extract impurities from crude metals.
[#344] Which of the following electrodes is used in strongly alkaline solution?
Correct Answer
(A) Mercury - mercuric oxide electrode
Explanation
Solution: Mercury - mercuric oxide electrode is used in strongly alkaline solution.
[#345] The laws of electrolysis are given by
Correct Answer
(B) Faraday
Explanation
Solution: Faraday's laws of electrolysis, in chemistry, are quantitative laws used to express magnitudes of electrolytic effects, first described by the English scientist Michael Faraday in 1833.