Calculate the number of molecules present in
(a) 1 kg oxygen,
(b) `1 dm^(3)` of hydrogen at S.T.P.

Explanation

To solve the problem of calculating the number of molecules in 1 kg of oxygen and 1 dm³ of hydrogen at STP, we will break it down into two parts.

### Part (a): Calculate the number of molecules in 1 kg of oxygen (O₂)

1. **Determine the molar mass of oxygen (O₂)**:
- The molar mass of O₂ = 16 g/mol (for one oxygen atom) × 2 = 32 g/mol.

2. **Convert 1 kg of oxygen to grams**:
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