(a) If in YCl,Y is sodium, the pH of the salt solution would be alkaline or basic. This is because the chloride ion (Cl−) is the conjugate base of the strong acid hydrochloric acid (HCl) and does not affect the pH significantly, while the sodium ion (Na+)is the conjugate acid of a weak base (NaOH) and can act as a source of hydroxide ions (OH−)in solution, increasing the pH.
(b) If in salt NH4X,X is a nitrate, its solution will give a green colour with a universal indicator. This is because ammonium ion (NH4+)is a weak acid that can partially dissociate to form hydrogen ions (H+)in the solution, making the solution acidic. Nitrate ion (NO3−)is a neutral ion and does not affect the pH. The green colour of the solution indicates a pH between 7 and 6.
(c) If ZCO3 is added to the blue litmus solution and Z is potassium, the blue litmus solution will turn pink or red. This is because the carbonate ion (CO32−) is a strong base that can accept hydrogen ions (H+)from water, forming bicarbonate ion (HCO3−)and hydroxide ion (OH−), and increasing the pH. The blue litmus solution, which is a pH indicator that turns red in acidic conditions, will be affected by the increased pH and turn pink or red.