Avogadro's lasw states that under conditions of constant temp. and pressure equal volume of gases contain equal no. of particles. Experimental investigation shows that at one atmosphere pressure and a temperature of 273 k, one mole of any gas occupies a volume of which is very close to 22.4 lit. Therefore, the number of moles in any gas sample canbe found by comparing its volume at STP with 22.4 lit.
Number of gram atoms of oxygen present in 0.3 gram mole of `H_(2)C_(2)O_(4).2H_(2)O` is

Options

A. 0.3
B. 0.6
C. 1.2
D. 1.8

Answer

To find the number of gram atoms of oxygen present in 0.3 gram mole of \( H_2C_2O_4 \cdot 2H_2O \) (oxalic acid dihydrate), we can follow these steps:

### Step 1: Determine the number of oxygen atoms in one molecule of oxalic acid dihydrate.

The molecular formula of oxalic acid dihydrate is \( H_2C_2O_4 \cdot 2H_2O \).

- In \( H_2C_2O_4 \):
- There are 4 oxygen atoms.

- In \( 2H_2O \):
- Each water molecule has 1 oxygen atom, and there are 2 water molecules, contributing 2 more oxygen atoms.

**Total oxygen atoms in one molecule of \( H_2C_2O_4 \cdot 2H_2O \)**:
\[ 4 \text{ (from } H_2C_2O_4\text{)} + 2 \text{ (from } 2H_2O\text{)} = 6 \text{ oxygen atoms} \]

### Step 2: Calculate the number of gram atoms of oxygen in 0.3 gram mole of oxalic acid dihydrate.

Since 1 mole of \( H_2C_2O_4 \cdot 2H_2O \) contains 6 moles of oxygen atoms, we can find the number of moles of oxygen in 0.3 moles of oxalic acid dihydrate.

**Calculation**:
\[ \text{Number of moles of oxygen} = 6 \text{ moles of oxygen per mole of } H_2C_2O_4 \cdot 2H_2O \times 0.3 \text{ moles of } H_2C_2O_4 \cdot 2H_2O \]
\[ = 6 \times 0.3 = 1.8 \text{ moles of oxygen} \]

### Conclusion:
The number of gram atoms of oxygen present in 0.3 gram mole of \( H_2C_2O_4 \cdot 2H_2O \) is **1.8**.

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