"Caustic" is a general term often used to refer to sodium hydroxide (NaOH), also known as lye or caustic soda.

The specific gravity of sodium hydroxide depends on the concentration of the solution.

Here's a breakdown:

* Solid NaOH: The specific gravity of solid sodium hydroxide is approximately 2.13.

* Solution: The specific gravity of a sodium hydroxide solution will vary depending on its concentration. You can find tables or calculators online that provide specific gravity values for different NaOH concentrations.

For example:

* A 50% NaOH solution has a specific gravity of approximately 1.52.

* A 30% NaOH solution has a specific gravity of approximately 1.33.

Important Note: Specific gravity is a ratio of the density of a substance to the density of water. It is a unitless value.

Always handle caustic solutions with extreme caution. They are corrosive and can cause severe burns. Wear appropriate protective gear and follow proper safety procedures.