Chemistry - Study Mode

[#506] Which one of the following elements is used in the manufacture of safety matches?
Correct Answer

(B) Phosphorus

Explanation

Solution: Red phosphorus is used in the manufacture of safety matches.

[#507] Which halide is used in making sensitive emulsion on photograhic film?
Correct Answer

(B) Silver bromide

Explanation

Solution: Silver bromide, a soft, pale-yellow, water insoluble salt well known for its unusual sensitivity to light. This property has allowed silver halides to become the basis of modern photographic materials.

[#508] Detergents clean surfaces on the principle of
Correct Answer

(B) Surface tension

Explanation

Solution: Detergents and soaps are used for cleaning because pure water can’t remove oily, organic soiling. Soap cleans by acting as an emulsifier. Basically, soap allows oil and water to mix so that oily grime can be removed during rinsing. Detergents were developed in response to the shortage of the animal and vegetable fats used to make soap during World War I and World War II. Detergents are primarily surfactants, which could be produced easily from petrochemicals. Surfactants lower the surface tension of water, essentially making it ‘wetter’ so that it is less likely to stick to itself and more likely to interact with oil and grease. Modern detergents contain more than surfactants. Cleaning products may also contain enzymes to degrade protein-based stains, bleaches to de-colour stains and add power to cleaning agents, and blue dyes to counter yellowing. Like soaps, detergents have hydrophobic or water-hating molecular chains and hydrophilic or water-loving components

[#509] A powerful eye irritant present in smog is
Correct Answer

(C) Peroxyacetyl nitrate

Explanation

Solution: Peroxyacetyl nitrate is a secondary pollutant present in photochemical smog. It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas. It is a lachrymatory substance.

[#510] Which of the following is not a natural source of air pollution ?
Correct Answer

(D) None of the above

Explanation

Solution: Natural pollution comes from natural sources like release of methane by cattle and paddy fields, carbon dioxide from plants and animals, dust storms, nitrogen oxides, ozone, volcanic eruptions, emission of natural gas, sol erosion, ultraviolet rays,etc. Mercury is not a cause of natural pollution.