The pH of a salt solution depends on the relative strengths of the acid and base from which it is formed:

1. $\text{NaNO}_3$ is a salt of a strong acid ($\text{HNO}_3$) and a strong base ($\text{NaOH}$). Its aqueous solution does not undergo hydrolysis and remains neutral with $\text{pH} = 7$ .
2. $\text{NH}_4\text{Cl}$ is a salt of a strong acid ($\text{HCl}$) and a weak base ($\text{NH}_4\text{OH}$). It undergoes cationic hydrolysis to form an acidic solution with $\text{pH} < 7$ .
3. $\text{CH}_3\text{COOK}$ and $\text{Na}_2\text{CO}_3$ are salts of weak acids ($\text{CH}_3\text{COOH}$ and $\text{H}_2\text{CO}_3$, respectively) and strong bases ($\text{KOH}$ and $\text{NaOH}$). Both undergo anionic hydrolysis to form basic solutions with $\text{pH} > 7$ . However, carbonic acid ($\text{H}_2\text{CO}_3$) is a weaker acid than acetic acid ($\text{CH}_3\text{COOH}$). Because it is formed from a weaker acid, the carbonate ion ($\text{CO}_3^{2-}$) is a stronger conjugate base than the acetate ion ($\text{CH}_3\text{COO}^-$). Therefore, $\text{CO}_3^{2-}$ undergoes hydrolysis to a greater extent, producing a higher concentration of $\text{OH}^-$ ions. As a result, the aqueous solution of $\text{Na}_2\text{CO}_3$ is more basic and has the highest pH among the given options.