The correct answer is: A. Dilute H2SO4
Specific gravity is the ratio of the density of a substance to the density of a reference substance. The reference substance is usually water, which has a density of 1 gram per cubic centimeter (g/cm3) at 4 degrees Celsius.
Dilute sulfuric acid has a density of 1.02 g/cm3, while concentrated sulfuric acid has a density of 1.84 g/cm3. Therefore, dilute sulfuric acid has a lower specific gravity than concentrated sulfuric acid.
Water has a density of 1 g/cm3, which is the same as the density of the reference substance. Therefore, water does not have a lower specific gravity than any of the other options.
Here is a table that summarizes the specific gravity of each option:
| Option | Specific gravity |
|—|—|
| Dilute H2SO4 | 1.02 g/cm3 |
| Concentrated H2SO4 | 1.84 g/cm3 |
| Water | 1 g/cm3 |