Practice MCQ Questions and answers on Chemistry-GK

Diamond has remarkable optical characteristics. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Combined with wide transparency, this results in the clear, colourless appearance of most natural diamonds. Small amounts of defects or impurities (about one per million of lattice atoms) colour diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion (ability to disperse light of different colours), which results in its characteristic luster. Excellent optical and mechanical properties, combined with efficient marketing, make diamond the most popular gemstone.

If lime water is kept in the air, it turns milky due to presence of carbon dioxide.

Diamond is harder than graphite because diamond has a more complex structure. Diamond’s structure is like many pentagons connected together, each pentagon sharing a side with another pentagon or each pentagon sharing a point with another pentagon. All the points are linked together in some way. Graphite’s structure is very loose, with its bonds forming layers. There will be one sheet of elements bonded together, but then another sheet of bonds of elements will lay on top of that, and there will be very weak bonds holding those sheets together.

It is because carbon dioxide does not support combustion. When sprayed on burning object it stops the supply of oxygen and extinguishes fire.

Anthracite coal contains 90 per cent of carbon.

One carat of diamond is equal to 200 mg.

Carbon dioxide is a reducing agent.

Diamond is a well known allotrope of carbon. The hardness and high dispersion of light of diamond make it useful for both industrial applications and jewelry. Diamond is the hardest known natural mineral.

Diamond is lustrous because its refractive index is high.

Dry ice is the solid form of carbon dioxide. It is used primarily as a cooling agent. Its advantages include lower temperature than that of water ice and not leaving any residue. It is useful for preserving frozen foods where mechanical cooling is unavailable.