Practice MCQ Questions and answers on Chemistry-GK

Since water and carbon dioxide are both compounds which contain oxygen, it is possible to obtain oxygen from either. The oxygen produced from photosynthesis is not released into the air. It is not until cellular respiration that oxygen is released. The oxygen comes from water. The water molecules are split at the “beginning” of photosynthesis for the electrons. These electrons eventually make their way to the electron transport chain, where oxygen is the final electron accept, and then released into the air. Scientists agree that there’s oxygen from ocean plants in every breath we take. Most of this oxygen comes from tiny ocean plants – called phytoplankton – that live near the water’s surface and drift with the currents. Like all plants, they photosynthesize – that is, they use sunlight and carbon dioxide to make food. A byproduct of photosynthesis is oxygen.

Alum is double sulphates having the composition M₂SO₄. M₂(SO₄)₃.24H₂O. Where M stands for monovalent basic radicals. Alums have Germicide properties and thus used in purification of water.

Brown stains in vessels and clothes generally indicate the presence of high quantities of iron. It causes reddish-brown staining of laundry, porcelain, dishes, utensils and even glassware. Manganese acts in a similar way but causes a brownish-black stain. Soaps and detergents do not remove these stains.

If water smells bad, then that odour can be removed by adding activated carbon.

Surface water is a better source of drinking water because it is poor in arsenic.

The formation of the lead sulphate products involves sulphuric acid, which is the electrolyte used in these batteries. During battery charge, lead sulphate is converted back to lead and lead dioxide, releasing sulphuric acid into the electrolyte.

Diethylamine is the strongest base in aqueous solution.

A 38% solution of sulphuric acid is used as an electrolyte in lead-acid battery.

Phenol is known as carbolic acid.

Lemons, oranges, limes, and other citrus fruits naturally possess high concentrations of citric acid. The juice of the lemon is about 5% to 6% citric acid, which gives lemons a sour taste. In fact, Citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice.