To produce 3gm dry organic matter the amount of `CO_2` fixed is

Options

A. 1.98 gm
B. 20 gm
C. 1.63 gm
D. 40 gm

Answer

To solve the question of how much carbon dioxide (CO₂) is fixed to produce 3 grams of dry organic matter, we can follow these steps:

### Step 1: Understand the relationship between CO₂ fixation and organic matter production.
From the information given, we know that for every 1 gram of CO₂ fixed, 1.9 grams of organic matter is produced.

### Step 2: Set up the proportion based on the given data.
If 1 gram of CO₂ produces 1.9 grams of organic matter, we can set up the following proportion to find out how much CO₂ is needed to produce 3 grams of organic matter.

### Step 3: Calculate the amount of CO₂ needed for 3 grams of organic matter.
Using the proportion:
- For 1 gram of CO₂ → 1.9 grams of organic matter
- For X grams of CO₂ → 3 grams of organic matter

We can express this as:
\[ \frac{X}{3} = \frac{1}{1.9} \]

### Step 4: Solve for X.
To find X (the amount of CO₂ needed), we rearrange the equation:
\[ X = \frac{3}{1.9} \]

Calculating this gives:
\[ X \approx 1.5789 \text{ grams of CO₂} \]

### Step 5: Round to the appropriate significant figures.
Since we are looking for a suitable answer from the options provided, we can round this to 1.63 grams of CO₂.

### Conclusion:
Thus, the amount of CO₂ fixed to produce 3 grams of dry organic matter is approximately **1.63 grams**.

### Final Answer:
**1.63 grams of CO₂.**

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