Calculate the number of atoms in each of the following :
52g of He.

Answer

To calculate the number of atoms in 52 g of helium (He), we can follow these steps:

### Step 1: Determine the atomic mass of helium.
The atomic mass of helium is approximately 4 g/mol.

### Step 2: Use Avogadro's number.
Avogadro's number (N_A) is \(6.022 \times 10^{23}\) atoms/mol. This means that 4 g of helium contains \(6.022 \times 10^{23}\) atoms.

### Step 3: Set up a proportion using the unitary method.
We know that:
- 4 g of He contains \(6.022 \times 10^{23}\) atoms.
- We need to find the number of atoms in 52 g of He.

Using the unitary method:
\[ \text{Number of atoms in 52 g of He} = \left(\frac{6.022 \times 10^{23} \text{ atoms}}{4 \text{ g}}\right) \times 52 \text{ g} \]

### Step 4: Perform the calculation.
\[ \text{Number of atoms in 52 g of He} = \left(\frac{6.022 \times 10^{23}}{4}\right) \times 52 \]
Calculating the fraction:
\[ \frac{6.022 \times 10^{23}}{4} = 1.5055 \times 10^{23} \]
Now multiply by 52:
\[ 1.5055 \times 10^{23} \times 52 = 7.82 \times 10^{24} \text{ atoms} \]

### Final Answer:
The number of atoms in 52 g of helium is \(7.82 \times 10^{24}\) atoms.

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