Chemistry - Study Mode

[#556] Which one of the following is used as preservative for foodstuff ?
Correct Answer

(A) Sodium Benzoate

Explanation

Solution: Sodium benzoate is a preservative. It is bacteriostatic and fungistatic under acidic conditions. It is most widely used in acidic foods such as salad dressings (vinegar), carbonated drinks (carbonic acid), jams and fruit juices (citric acid), pickles (vinegar), and condiments. It is also used as a preservative in medicines and cosmetics.

[#557] The acid which fails to liberate carbon dioxide from sodium bicarbonate is :
Correct Answer

(D) Sulphuric acid

Explanation

Solution: Sodium bicarbonate and organic acid (Formic acid, Acetic acid, Carbonic acid, etc) react vigorously to liberate carbon dioxide. For example, Sodium bicarbonate (NaHCO 3 ) when treated with acetic acid reacts vigorously to liberate carbon dioxide.

[#558] Which of the following is used in welding broken pieces of iron rails and machine parts?
Correct Answer

(C) Aluminium powder

Explanation

Solution: Aluminum powder is a highly flammable powder created by grinding aluminum into fine grains of material. In times past, this flammable metal powder was used in photography to create bright flashes during a photographic session. Today, aluminum powder is one of the tools utilized in various applications of pyrotechnics, including the creation of fireworks displays. Used primarily as an inlay compound, the aluminum powder can easily be used to set cut pieces of wood into position and also fill in any tiny gaps that may be present at the joints. Since only a minute amount of powder is necessary for functions of this type, the chances of ignition are somewhat limited.

[#559] Of the following commonly used materials, the one that is not an alloy is
Correct Answer

(D) Copper

Explanation

Solution: Of the following commonly used materials, the one that is not an alloy is copper.

[#560] The manufacture of iron from iron ore involves the process of
Correct Answer

(B) Reduction

Explanation

Solution: The manufacture of iron ore involves the process of reduction. Important ores of iron: Haematite, Magnetite.