Aqueous solution of NaCl contains equal number of H+ and OH- ions,hence it is neutral in nature. On other hand,sodium carbonate is a salt of weak acid H₂CO₃ and strong baseNaOH. ... Thus salt solution contains OH- ions. Hence aqueous solution of sodium carbonate is basic in nature.

Explanation:

What is pH?
pH is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm of the concentration of hydrogen ions (H+) in a solution. pH ranges from 0 to 14, with 7 being neutral, less than 7 being acidic, and greater than 7 being basic or alkaline.

Why is NaCl neutral?
Sodium chloride (NaCl) is an ionic compound made up of a cation (Na+) and an anion (Cl-) held together by ionic bonds. When NaCl is dissolved in water, it dissociates into Na+ and Cl- ions. Neither of these ions can react with water to produce H+ or OH- ions. Hence, the solution remains neutral with a pH of 7.

Why is Na2CO3 basic?
Sodium carbonate (Na2CO3) is also an ionic compound made up of two sodium cations (Na+) and one carbonate anion (CO32-) held together by ionic bonds. When Na2CO3 is dissolved in water, it dissociates into Na+ and CO32- ions. The carbonate ion can react with water to produce bicarbonate (HCO3-) and hydroxide (OH-) ions as follows:

CO32- + H2O → HCO3- + OH-

This reaction increases the concentration of OH- ions in the solution, making it basic or alkaline. Hence, the pH of a solution of Na2CO3 in water will be greater than 7.