An ice cube floats in a glass of water. What happens to the level of water in the glass when ice melts? 

Solution:

When an ice cube floats in water, it displaces an amount of water equal to the weight of the ice cube. As the ice melts, it turns into water and occupies the volume that was previously displaced by the ice.

Ice is less dense than water, which is why it floats. The volume of water produced by the melting ice will be exactly equal to the volume of water that was displaced by the ice cube while it was floating.

Therefore, when the ice melts, the water level in the glass remains the same.

∴ The correct answer is option 3: Remains the same.