Answer:(d) An antacid
Sample solution turn pH paper yellowish-orange which confirms the acidic nature of the sample. To make the colour to greenish-blue, we have to add an antacid.
The substance which is used to relieve indigestion, caused by too much HCl secretion in the stomach, it is called as Antacid.
- Acidity in the stomach causes the sensation of heartburn, antacids are taken to relieve this sensation.
- They are taken orally to suppress the effects of acidity. Antacids are actually alkaline ions that directly neutralize the gastric acids of the stomach.