Question

The poisonous gas present in the exhaust fumes of car is: (a) \(\mathrm{CO}_{2}\) (b) \(\mathrm{CO}\) (c) \(\mathrm{CH}_{4}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{2}\)

Short answer

The poisonous gas present in car exhaust is carbon monoxide \((\mathrm{CO})\).

Step-by-step solution

Identifying Harmful Substances

Start by identifying the substances given in the options. They are different chemical compounds: carbon dioxide \(\mathrm{CO}_2\), carbon monoxide \(\mathrm{CO}\), methane \(\mathrm{CH}_4\), and acetylene \(\mathrm{C}_2\mathrm{H}_2\).

Understanding Car Exhaust

Car exhaust contains various gases produced by combustion in the engine. Among them, some are harmful to humans and the environment. Common harmful exhaust gases include carbon monoxide \((\mathrm{CO})\) and nitrogen oxides.

Evaluating Each Option

Evaluate each option: \(\mathrm{CO}_2\) is a normal product of combustion and not particularly harmful in normal concentrations. \(\mathrm{CH}_4\) is not commonly found in significant amounts in car exhaust. Similarly, \(\mathrm{C}_2\mathrm{H}_2\) is not typical in car exhaust. \(\mathrm{CO}\), however, is a highly poisonous gas present in car exhaust as a result of incomplete combustion.

Selecting the Correct Option

Based on the evaluation, \(\mathrm{CO}\) (carbon monoxide) is the poisonous gas that is present in car exhaust fumes.

Key concepts

Car Exhaust Emissions

Car exhaust emissions refer to the gases released when fuel combusts within a vehicle’s engine. During this process, the engine burns fuel—such as gasoline or diesel—and converts it to energy to power the car. However, not all of the fuel is perfectly combusted, resulting in several byproducts being expelled into the atmosphere. These emissions include a mix of both harmless and harmful gases.
One of the major components of car exhaust is carbon dioxide (\(\mathrm{CO}_2\)), which, while contributing to global warming, isn't directly harmful in small concentrations. Other gases, however, are highly detrimental to both human health and the environment. The combination and concentration of these pollutants depend on factors such as fuel type, engine efficiency, and maintenance of the vehicle.
To reduce the negative impact of car exhaust emissions, measures like regular vehicle maintenance, using cleaner fuels, and technologies such as catalytic converters are essential.

Combustion Products

Products of combustion in engines dictate what ultimately ends up in the car's exhaust. Combustion is the chemical process of burning a fuel, such as gasoline, mixing it with air to create energy. Ideally, complete combustion converts fuel into water vapor and carbon dioxide.
However, in real-world conditions, combustion is rarely perfect. Incomplete combustion can occur due to inadequate oxygen or other suboptimal conditions. This leads to various unburned hydrocarbons and harmful gases like carbon monoxide (\(\mathrm{CO}\)).
A car engine's efficiency in achieving complete combustion can directly influence the emission profile. Better combustion translates to fewer harmful byproducts. Innovations such as direct fuel injection and turbocharging are examples of technological advancements aimed at improving combustion efficiency.

Harmful Gases in Vehicles

Car exhaust emissions include a range of harmful gases. Carbon monoxide (\(\mathrm{CO}\)) stands out as one of the most dangerous. It is a colorless, odorless gas formed from incomplete combustion in car engines. When inhaled, it can prevent oxygen from being delivered to the body, leading to serious health risks.
Other harmful gases include nitrogen oxides (\(\mathrm{NO}_x\)), which contribute to smog and acid rain. Volatile organic compounds (VOCs) are another group affecting air quality and health. Even while gases like sulfur dioxide (\(\mathrm{SO}_2\)) are less prominent, they are still a concern especially in diesel engines.
Limiting these pollutants involves more efficient engine designs, regular vehicle servicing, and the use of filtration systems like catalytic converters. These measures can help reduce emissions, making vehicles less harmful to both people and the environment.