Introduction:
Sodium acetate is a sodium salt of acetic acid and is commonly found in the form of a white crystalline powder. When dissolved in water, it forms an aqueous solution of sodium acetate.

Aqueous Solution of Sodium Acetate:
When sodium acetate is dissolved in water, it ionizes to release sodium ions (Na+) and acetate ions (CH3COO-). The presence of these ions in the solution determines its pH and acidity or alkalinity.

pH of Sodium Acetate Solution:
The pH of a solution depends on the concentration of hydrogen ions (H+) it contains. Acids release hydrogen ions, whereas bases release hydroxide ions (OH-). The concentration of these ions determines the pH scale. A neutral solution has a pH of 7, acidic solutions have a pH less than 7, and alkaline (basic) solutions have a pH greater than 7.

Acidity or Alkalinity of Sodium Acetate Solution:
Sodium acetate is the conjugate base of acetic acid. Acetic acid is a weak acid that partially ionizes in water to release hydrogen ions. However, when sodium acetate is dissolved in water, it acts as a base and reacts with water to accept hydrogen ions, resulting in the formation of acetic acid and hydroxide ions.

The reaction can be represented as follows:
CH3COONa + H2O → CH3COOH + NaOH

The presence of hydroxide ions in the solution makes it alkaline. Therefore, an aqueous solution of sodium acetate is alkaline.

Conclusion:
The correct answer is option 'D'. An aqueous solution of sodium acetate is alkaline because it reacts with water to form hydroxide ions. This alkalinity is due to the reaction between sodium acetate and water, which results in the production of acetic acid and hydroxide ions.