Question

What happened when an ice block that floats in a glass of water that is filled to the brim melts?

Answer 1

When an ice block that floats in a glass of water that is filled to the brim melts the water level remains the same.

When the ice has melted, it turns into water of exactly the same volume as it displaced before. So the added volume is the same, so the level of the water will not change.