Chemistry - Study Mode

[#1091] Petroleum consists of a mixture of
Correct Answer

(C) Hydrocarbons

Explanation

Solution: Petroleum is a mixture of a very large number of different hydrocarbons

the most commonly found molecules are alkanes (paraffins), cycloalkanes (naphthenes), aromatic hydrocarbons, or more complicated chemicals like asphaltenes.

[#1092] The temperature of oxy-acetylene flame is around
Correct Answer

(C) 3600°C

Explanation

Solution: The oxy-acetylene flame is generated by burning acetylene (C₂H₂) in the presence of oxygen (O₂), creating one of the hottest known flame types used in industrial applications. When acetylene combusts in oxygen, it undergoes a chemical reaction that releases a significant amount of heat: C₂H₂ + 2.5O₂ → 2CO₂ + H₂O + Heat This combustion produces a flame with two distinct zones: an inner cone and an outer envelope. The inner cone is the hottest part and is typically used for welding and cutting purposes. The temperature of the inner cone in a neutral oxy-acetylene flame (balanced oxygen and acetylene) reaches approximately 3600°C (about 6530°F). Such a high temperature is ideal for melting most metals, including steel and iron, which makes the flame extremely valuable in metalworking industries. The flame can be adjusted to three types depending on the oxygen-to-acetylene ratio: Neutral Flame: Equal oxygen and acetylene

used for welding most metals. Carburizing (Reducing) Flame: Excess acetylene

used for specific applications like welding high-carbon steels. Oxidizing Flame: Excess oxygen

used for cutting metals. Among these, the neutral flame produces the highest and most efficient heat, reaching up to 3600°C. Therefore, the correct answer is 3600°C (Option C).

[#1093] The major harmful gas emitted by automobile vehicle which causes air pollution is
Correct Answer

(A) Carbon Monoxide

Explanation

Solution: Carbon monoxide is the major harmful gas emitted by the automobile vehicles which causes air pollution. Carbon monoxide (CO) - A product of incomplete combustion, carbon monoxide reduces the blood’s ability to carry oxygen

overexposure (carbon monoxide poisoning) may be fatal. Carbon Monoxide poisoning is a major killer. Carbon monoxide is a temporary atmospheric pollutant in some urban areas, chiefly from the exhaust of internal combustion engines (including vehicles, portable and back-up generators, lawn mowers, power washers, etc.), but also from incomplete combustion of various other fuels (including wood, coal, charcoal, oil, paraffin, propane, natural gas, and trash). Carbon monoxide is, along with aldehydes, part of the series of cycles of chemical reactions that form photochemical smog

[#1094] Which of the toxic heavy metals is found in modern tannery industries ?
Correct Answer

(C) Chromium

Explanation

Solution: Chromium is mainly found in waste from the chrome tanning process

it occurs as part of the retanning system and is displaced from leathers during retanning and dyeing processes. This chrome is discharged from processes in soluble form

however, when mixed with tannery waste waters from other processes (especially if proteins are present), the reaction is very rapid. Precipitates are formed, mainly protein-chrome, which add to sludge generation. If chrome discharges are excessive, the chromium might remain in the solution. Even in low concentrations, it has a toxic effect upon daphnia, thus disrupting the food chain for fish life and possibly inhibiting photosynthesis.

[#1095] Which of the following has pH value 7?
Correct Answer

(A) Pure Water

Explanation

Solution: In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, being neither an acid nor basic
so it has pH value of 7.