A helium-filled balloon will float in air because

Options

A. there is more air than helium.
B. helium is as dense as air.
C. helium is less dense than air.
D. helium is more dense than air.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Concept of Density:**
- Density is defined as mass per unit volume (Density = Mass/Volume).
- Helium is a gas that has a lower density compared to the density of air.

2. **Comparing Densities:**
- The density of helium is approximately 0.1785 kg/m³, while the density of air is about 1.225 kg/m³ at sea level.
- Since helium's density is less than that of air, this is a key factor in understanding why the balloon floats.

3. **Application of Archimedes' Principle:**
- According to Archimedes’ principle, an object will float if the buoyant force acting on it is greater than or equal to the weight of the object.
- The buoyant force is equal to the weight of the air displaced by the balloon.

4. **Buoyant Force and Weight of the Balloon:**
- The weight of the helium-filled balloon is less than the weight of the air it displaces because helium is less dense than air.
- Therefore, the upward buoyant force acting on the balloon is greater than the downward gravitational force acting on it.

5. **Conclusion:**
- Since the buoyant force is greater than the weight of the helium-filled balloon, the balloon will float in the air.

**Final Answer:**
A helium-filled balloon will float in air because helium is less dense than air.

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