Molal elevation constant is also known as:

Ebullioscopic constant

The correct answer is Option (1) → Ebullioscopic constant.

The molal elevation constant refers to a property of solvents that quantifies the elevation of the boiling point when a solute is added. This constant is specifically known as the ebullioscopic constant.

Definitions of the Options:

1. Ebullioscopic Constant:

This is the constant used to calculate the elevation in boiling point (ΔT_b) of a solvent when a non-volatile solute is added. It is denoted as \( K_b \).

2. Gas Constant:

This is a universal constant (denoted as \( R \)) that appears in the ideal gas law equation and is not related to the elevation of boiling point.

3. Henry's Constant:

This constant relates to the solubility of gases in liquids and is defined in Henry's law. It is not related to boiling point elevation.

4. Cryoscopic Constant:

This is the constant used to determine the depression of the freezing point (ΔT_f) of a solvent when a solute is added. It is denoted as \( K_f \) and is not the same as the molal elevation constant.

Conclusion

The molal elevation constant is also known as the: Ebullioscopic constant.