Chemistry - Study Mode

[#256] 24 carat of diamond is equal to
Correct Answer

(A) 480 mg

Explanation

Solution: 24 carat of diamond is equal to 480 mg.

[#257] 1 carat of diamond is equal to
Correct Answer

(A) 200 mg

Explanation

Solution: 1 carat of diamond is equal to 200 mg.

[#258] Where does the oxygen that keeps us alive come from?
Correct Answer

(D) Water

Explanation

Solution: 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.

[#259] In chemical terms, what are alums used for purifying water for drinking purposes ?
Correct Answer

(C) Double sulphates

Explanation

Solution: Alum is double sulphates having the composition M 2 SO 4 . M 2 (SO 4 ) 3 .24H 2 O.
Where M stands for monovalent basic radicals. Alums have Germicide properties and thus used in purification of water.

[#260] Brown stains in vessels and clothes indicate the presence of high quantities of ________ in water.
Correct Answer

(D) None of these

Explanation

Solution: 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.