Answer:
HCl and NaCl option c
Explanation:
According to the pH scale interpretation a lower pH means that its is more acidic, while a higher pH means that it is more basic.
Simply put a pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.
From the question above c fits in the option with the lower pH meaning its a strong acid and it tends more towards 0 than 7.
A solution, containing a buffer, is one that maintains a relatively constant pH.
NH3 and NH4Cl ;H3PO4 and NaH2PO4 are an acid/base conjugate pair each. They will make an excellent buffer.
NaOH and NH3 would rather make a slightly basic mixture
NH2 and HC2H3O2 (acetic acid) slightly basic mixture ..
Solution c has the lowest pH.