Chemistry - Study Mode

[#1101] Which of the following is not a gaseous air pollutant?
Correct Answer

(B) Hydrocarbon

Explanation

Solution: The gaseous air pollutants of primary concern in urban settings include sulfur dioxide, nitrogen dioxide, and carbon monoxide
these are emitted directly into the air from the combustion of fossil fuels.Smoke, a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion, is also a pollutant. Hydrocarbon is an organic compound consisting entirely of hydrogen and carbon.

[#1102] Among the following iron ores, the highest percentage of iron content is found in–
Correct Answer

(A) Haemetite

Explanation

Solution: Hematite, also spelled haematite, heavy and relatively hard oxide mineral, ferric oxide (Fe 2 O 3 ), that constitutes the most important iron ore because of its high iron content (70 percent) and its abundance. Its name is derived from the Greek word for “blood,” in allusion to its red colour. Many of the various forms of hematite have separate names. The steel-gray crystals and coarse-grained varieties have a brilliant metallic lustre and are known as specular iron ore
thin scaly types are called micaceous hematite. Much hematite occurs in a soft, fine-grained, earthy form called red ochre or ruddle. Intermediate between these types are compact varieties, often with a reniform surface (kidney ore) or a fibrous structure (pencil ore). Red ochre is used as a paint pigment
a purified form, rouge, is used to polish plate glass. The most important deposits of hematite are sedimentary in origin. The world’s largest production (nearly 75 million tons of hematite annually) comes from a sedimentary deposit in the Lake Superior district in North America.

[#1103] Which one of the following contributes largely to the ‘green house effect’ ?
Correct Answer

(D) Water vapour

Explanation

Solution: The primary greenhouse gases in the Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. When these gases are ranked by their direct contribution to the greenhouse effect in percentage terms, the most important are: Water vapour: 36-72 per cent
Carbon dioxide: 9-26 per cent
Methane: 4-9 per cent
and Ozone: 3-7 per cent.

[#1104] Catalyst is a substance which
Correct Answer

(A) Increases the rate of the reaction

Explanation

Solution: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction itself. It achieves this by providing an alternative reaction pathway with a lower activation energy, which allows reactant molecules to more easily reach the transition state and form products. Here's a breakdown of the options: Option A: Increases the rate of the reaction : This option is correct . Catalysts are known for their ability to speed up chemical reactions, making them more efficient. Option B: Decreases the rate of reaction : This statement is not correct. Catalysts do not slow down reactions
they accelerate them. Option C: Has no action on the rate of the reaction : This statement is not correct. Catalysts specifically exist to increase the rate of chemical reactions. Option D: None of these : This is not the correct option because Option A (Increases the rate of the reaction) is accurate. Therefore, the correct answer is Option A: Increases the rate of the reaction .

[#1105] Zinc sulphide is commonly used as
Correct Answer

(C) Rodenticide

Explanation

Solution: Rodenticides are a category of pest control chemicals intended to kill rodents. Metal phosphides have been used as a means of killing rodents and are considered single-dose fast acting rodenticides (death occurs commonly within 1-3 days after single bait ingestion). A bait consisting of food and a phosphide (usually zinc phosphide) is left where the rodents can eat it. The acid in the digestive system of the rodent reacts with the phosphide to generate the toxic phosphine gas. This method of vermin control has possible use in places where rodents are resistant to some of the anticoagulants, particularly for control of house and field mice
zinc phosphide baits are also cheaper than most second-generation anticoagulants, so that sometimes, in the case of large infestation by rodents, their population is initially reduced by copious amounts of zinc phosphide bait applied, and the rest of population that survived the initial fast-acting poison is then eradicated by prolonged feeding on anticoagulant bait.