Practice MCQ Questions and answers on Chemistry-GK

There are three forms of pure carbon: graphite, coal and diamond. Among coal, Anthracite has the highest carbon content, the fewest impurities, and the highest calorific content of all types of coal except for graphite. Anthracite is the most metamorphosed type of coal in which the carbon content is between 92.1% and 98%.

Carbon footprint can be reduced by recycling waste materials, using energy efficient appliances and commuting by public transport.

Carbon monoxide (CO) is a colourless, odorless, and tasteless gas that is slightly lighter than air. It is toxic to humans and animals when encountered in higher concentrations, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere it is spatially variable, short lived, having a role in the formation of ground-level ozone. Carbon monoxide is colourless, odorless, and tasteless, but highly toxic. It combines with hemoglobin to produce carboxyhemoglobin, which is ineffective for delivering oxygen to bodily tissues. Concentrations as low as 667 ppm may cause up to 50% of the body’s hemoglobin to convert to carboxyhemoglobin. A level of 50% carboxyhemoglobin may result in seizure, coma, and fatality.

Water being heavier than petrol slips down permitting the petrol to rise to the surface and continue to burn. Also, the existing temperature is so high that most of the water poured on the fire evaporates even before it can extinguish the fire.

Graphite is used as a lubricant in heavy machines. it is made of carbon atoms arranged in sheets of hexagonal units - looks a lot like chicken-wire. Another sheet forms on top of this and so on. There is no proper connection (in ideal graphite) between the sheets, so they are able to slide freely over each other without breaking any bonds.

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, KClO₃), 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.

Water gas is a mixture of carbon monoxide (CO) and hydrogen (H₂) produced by passing steam over red-hot coke using the endothermic reaction.

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.

Mercury - mercuric oxide electrode is used in strongly alkaline 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.