`CO_2` and `H_2 O` absorbs strongly in the infrared rrgion and its presence in the atmospheere dectrases the loss fo heat form the enrth by radistiion . This global warming is called the greenhouse effect (other gases , including the oxides of nitraongen form car exhauset freons from aerosols and refrigeratirs and methane from bacteria in the soil and in the rument cows , also add to the reeenhouse effect ). The concentration fo atmospheric `CO_2` has increased by `10%` . The is rsulting in the increase in the mean temperature fo the earth by `2. 5^@ C`, varying form `2^@ C` t the equlator to `4^@ C` at the poles . This could have dramatic effects on the climate.
Instead of monitoring carbon dioxide suggest another gas that scientists could studey to substantiate the fact that ` CO_2` conentration is steadily increasing in the atmosphere ?

Options

A. `N_2O`
B. `O_2`
C. `CH_4`
D. `O_3`

Answer

To solve the question regarding which gas scientists could study to substantiate the increasing concentration of CO₂ in the atmosphere, we can follow these steps:

### Step 1: Understand the Greenhouse Effect
The greenhouse effect is primarily caused by gases like CO₂ and H₂O, which absorb infrared radiation and trap heat in the atmosphere. This leads to global warming.

**Hint:** Remember that greenhouse gases trap heat and contribute to temperature increases.

### Step 2: Identify Other Gases Contributing to the Greenhouse Effect
The question mentions other gases such as nitrogen oxides, methane (CH₄), and Freon. These gases also contribute to the greenhouse effect but may not directly correlate with the increase in CO₂.

**Hint:** Look for gases that are related to combustion or biological processes that might indicate changes in CO₂ levels.

### Step 3: Analyze the Options Provided
The options given are:
- Option A: N₂O (Nitrous oxide)
- Option B: O₂ (Oxygen)
- Option C: CH₄ (Methane)
- Option D: O₃ (Ozone)

**Hint:** Consider which of these gases has a relationship with CO₂ levels and can indicate changes in its concentration.

### Step 4: Consider the Relationship Between CO₂ and O₂
As CO₂ concentration increases due to combustion and respiration, the concentration of O₂ tends to decrease because it is consumed in these processes. Therefore, monitoring O₂ levels can provide insight into the changes in CO₂ levels.

**Hint:** Think about the balance of gases in the atmosphere and how one might affect the other.

### Step 5: Conclusion
Based on the analysis, the best gas to monitor to substantiate the increasing concentration of CO₂ in the atmosphere is O₂ (Option B). This is because a decrease in O₂ levels can indicate an increase in CO₂ levels due to combustion and respiration processes.

**Final Answer:** Option B: O₂