Final answer:
A block with a mass of 25 kg and volume of 0.02 m³ has a density of 1250 kg/m³, which is greater than the density of water (1000 kg/m³), so the block will sink.
Step-by-step explanation:
To determine whether a block will sink, float, or stay still in a fluid like water, we need to compare the block's density with that of water. The density of the block is calculated by dividing its mass by its volume. Given a block with a mass of 25 kg and a volume of 0.02 m³, its density is 1250 kg/m³ (25 kg / 0.02 m³). The density of freshwater is approximately 1000 kg/m³. Since the density of the block is greater than the density of water, the block will sink.