Calculate the number of atoms in 1g of helium

Options

A. `1.506 xx 10^(23) ` atoms
B. `1.605 xx 10^(32) ` atoms
C. `1.056 xx 10^(25)` atoms
D. None of these

Explanation

To calculate the number of atoms in 1 gram of helium, follow these steps:

### Step 1: Determine the molar mass of helium.
The molar mass of helium (He) is approximately 4 grams per mole (g/mol).

### Step 2: Calculate the number of moles in 1 gram of helium.
Using the formula:

\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

Substituting the values:

\[ \text{Number of moles} = \frac{1 \text{ g}}{4 \text{ g/mol}} = 0.25 \text{ moles} \]

### Step 3: Use Avogadro's number to find the number of atoms.
Avogadro's number states that 1 mole of any substance contains \(6.022 \times 10^{23}\) entities (atoms, molecules, etc.).

To find the number of atoms in 0.25 moles of helium:

\[ \text{Number of atoms} = \text{Number of moles} \times \text{Avogadro's number} \]

Substituting the values:

\[ \text{Number of atoms} = 0.25 \text{ moles} \times 6.022 \times 10^{23} \text{ atoms/mole} \]

Calculating this gives:

\[ \text{Number of atoms} = 1.5055 \times 10^{23} \text{ atoms} \]

### Final Answer:
The number of atoms in 1 gram of helium is approximately \(1.5055 \times 10^{23}\) atoms.

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