One mole of a substance present in 1 kg of solvent. The correct statement regarding above solution is:

Molal concentration

The correct answer is option 3. Molal concentration.

In chemistry, there are several ways to express the concentration of a solution, and two common ones are molarity and molality.

1. Molarity (M): Molarity is defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L). Mathematically, it can be represented as:

\[ M = \frac{\text{Number of moles of solute}}{\text{Volume of solution (in liters)}} \]

Molarity is affected by changes in temperature and pressure, as it depends on volume.

2. Molality (m): Molality is defined as the number of moles of solute per kilogram of solvent. It is expressed in moles per kilogram (mol/kg). Mathematically, it can be represented as:

\[ m = \frac{\text{Number of moles of solute}}{\text{Mass of solvent (in kilograms)}} \]

Molality is independent of changes in temperature, as it is based on the mass of the solvent, which remains constant regardless of temperature changes.

Given that one mole of a substance is present in 1 kg of solvent, this situation describes molal concentration because it indicates that one mole of solute is dissolved in each kilogram of solvent, regardless of the volume of the solution. Therefore, the correct statement regarding this solution is (3) Molal concentration.