Indoor Air Pollution

Step 1: Understanding the given data.
Coal burn rate = 1 kg/s
Sulfur content in coal = 3%
The amount of sulfur in the coal is .
Step 2: Convert sulfur to SO2.
For each kg of sulfur in the coal, the equivalent mass of SO2 is given by the molecular weight ratio of SO2 to sulfur. The molecular weight of sulfur (S) is 32 g/mol, and for SO2, it is 64 g/mol. Hence, the ratio is: Therefore, for every kg of sulfur, 2 kg of SO2 is emitted.
Step 3: Calculate the SO2 emission rate.
The rate of SO2 emission is: Step 4: Convert SO2 emission to kg/day.
To find the total emission in a day: Step 5: Final answer.
The SO2 emitted is

The question asks about the unit used to measure sound intensity level. Let's examine the options provided:

1. Hertz: This is a unit of frequency, which measures the number of cycles per second of a periodic phenomenon. It is not used to measure sound intensity level.
2. Decibel: This is the correct option. The decibel (dB) is a logarithmic unit used to measure the intensity of sound. It quantifies sound levels relative to a reference level, typically the threshold of hearing, which is defined as 0 dB.
3. Pascal: This unit is used to measure pressure. While sound waves do create pressure variations, the pascal is not used to measure the sound intensity level directly.
4. Joule: This unit measures energy or work. It is not related to measuring sound intensity level.

Therefore, the correct answer is Decibel. This is because the sound intensity level indicates how much sound power passes through a certain area, and the decibel scale provides a convenient way to express these levels in a manageable range, using a logarithmic scale.

To elaborate, sound intensity level in decibels (dB) is calculated using the formula:

where:

• is the sound intensity level in decibels.
• is the intensity of the sound wave.
• is the reference intensity, usually , which is the threshold of human hearing.

This logarithmic scale means that an increase of 10 dB represents a tenfold increase in intensity, which makes it easier to represent the wide range of hearing in human experiences.

To determine which air pollutants are mainly responsible for acid rain, we need to understand the chemical processes involved in its formation.

Acid rain is primarily caused by the emissions of sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) into the atmosphere. These gases are produced from burning fossil fuels like coal, oil, and natural gas, as well as from industrial processes and vehicle emissions.

1. Sulfur Dioxide (SO₂): This gas reacts with oxygen to form sulfur trioxide (SO₃), which further combines with water vapor in the atmosphere, forming sulfuric acid (H₂SO₄).

The chemical reaction is shown below:

1. Nitrogen Dioxide (NO₂): This gas reacts with water to form nitric acid (HNO₃).

The chemical reaction is:

Hence, the formation of sulfuric acid and nitric acid contributes to the acidity of rain. As acid rain falls on the ground, it can have harmful impacts on aquatic life, plants, and infrastructure.

Now, let's examine the provided options:

1. CO and CO₂: Carbon monoxide (CO) and carbon dioxide (CO₂) are not significantly involved in acid rain formation. These gases contribute to other environmental issues such as global warming and air pollution but not acid rain.
2. NO₂ and SO₂: As explained above, these are the primary pollutants responsible for acid rain.
3. O₃ and PAN: Ozone (O₃) and peroxyacetyl nitrate (PAN) are secondary pollutants involved in photochemical smog and not acid rain.
4. NH₃ and CH₄: Ammonia (NH₃) and methane (CH₄) do not play a significant role in acid rain. They contribute to other phenomena like the greenhouse effect and eutrophication.

Therefore, the correct answer is NO₂ and SO₂, as they are the main pollutants responsible for acid rain formation.