If a liquid's specific gravity is 0.8, which statement about its weight per unit volume relative to water is correct?

Answer: C — Weighs Less Than Water

Specific gravity tells you how dense a liquid is compared with water. An SG of 0.8 means the liquid’s density is 0.8 times that of water. Since weight per unit volume (weight density) at the same gravity scales with density, this liquid will weigh 0.8 times as much per unit volume as water. So it weighs less than water. If SG were greater than 1, it would weigh more per unit volume; if it were 1, it would weigh the same.