Complete the following using the correct word given in the brackets.
The density of hydrogen chloride is _____than air. (lower/higher) 

Explanation

To solve the question regarding the density of hydrogen chloride (HCl) in comparison to air, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Density**: Density is defined as mass per unit volume. It is a measure of how much matter is packed into a given space.

2. **Comparison with Air**: Air has a density of approximately 1.225 kg/m³ at sea level. To determine whether hydrogen chloride is lower or higher in density than air, we need to know the density of hydrogen chloride.

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