This question tests knowledge about common acid-base indicators, specifically phenolphthalein. Indicators are substances that change color depending on the pH of the solution they are in. Phenolphthalein is widely used in titrations to detect the endpoint.
Correct Option: D) Pink
This question tests knowledge about common acid-base indicators, specifically phenolphthalein. Indicators are substances that change color depending on the pH of the solution, helping to determine if a solution is acidic, basic, or neutral.
A) No (meaning no color or colorless). Phenolphthalein is colorless in acidic solutions (pH < 8.2).
The question describes a neutralisation reaction and asks for the name of the new substance formed along with water and heat. Understanding the products of an acid-base neutralisation reaction is key to answering this question.
\[ \text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water} + \text{Heat} \]
\[ \text{HCl} (\text{acid}) + \text{NaOH} (\text{base}) \rightarrow \text{NaCl} (\text{salt}) + \text{H}_2\text{O} (\text{water}) + \text{Heat} \]
Correct Option: C) Salt is the new substance formed along with water and heat during a neutralisation reaction.
The question asks for the specific term used to describe the chemical reaction between an acid and a base. We need to recall the fundamental definitions of chemical reactions, particularly those involving acids and bases.
Correct Option: B) Neutralisation
The question asks to identify the acid present in the human stomach that aids in food digestion. This is a direct knowledge-based question related to human biology and chemistry.
The stomach lining contains glands that produce gastric juice. A key component of this juice is hydrochloric acid (HCl). Hydrochloric acid provides a highly acidic environment (pH 1.5 to 3.5) which is essential for:
Therefore, hydrochloric acid is the correct answer.
D) Hydrochloric acid — Hydrochloric acid (HCl) is secreted by the parietal cells in the stomach lining. It creates the acidic environment necessary for protein digestion and acts as a protective barrier against pathogens.
Indigestion is often caused by an excess of acid in the stomach. To relieve this, an antacid is required. Antacids are bases that neutralize the excess stomach acid. We need to identify which of the given options acts as a base.
Correct Option: A) Milk of magnesia is magnesium hydroxide, \( \text{Mg(OH)}_2 \), which is a weak base. It reacts with the excess hydrochloric acid in the stomach to form water and magnesium chloride, thereby neutralizing the acid and relieving indigestion.