Acid-base Indicators Quiz

Natural indicators are substances that are found in nature and can be used to determine the pH of a solution. These indicators change color depending on the acidity or alkalinity of a solution. Examples of natural indicators include red cabbage juice, turmeric, and beetroot juice. These indicators are preferred over synthetic indicators as they are easily available, cost-effective, and environmentally friendly. They have been used for centuries in various applications such as in cooking, medicine, and chemistry experiments.

Bases are sometimes called alkalis because alkalis are a subset of bases. Alkalis are specifically those bases that are soluble in water. Bases, on the other hand, are substances that can accept protons or donate pairs of electrons. Therefore, all alkalis are bases, but not all bases are alkalis.

Yes, an amphoteric substance can act as both an acid and a base. This means that it can donate a proton (act as an acid) in the presence of a stronger base, and it can accept a proton (act as a base) in the presence of a stronger acid. Examples of amphoteric substances include water, amino acids, and some metal oxides.

Phenolphthalein is the indicator that turns pink in an alkali solution. It is a commonly used indicator in chemistry experiments to determine the presence of a base or alkali. In an alkaline solution, phenolphthalein changes from colorless to pink, indicating the basic nature of the solution. This color change occurs due to the reaction between phenolphthalein and hydroxide ions present in the alkali solution. Therefore, phenolphthalein is the correct answer in this case.

Strong acids completely dissociate in water, meaning that they break apart into ions. This is because strong acids are highly reactive and readily donate hydrogen ions (H+) to the water molecules. As a result, the concentration of H+ ions in the solution increases significantly. Examples of strong acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3). In contrast, weak acids only partially dissociate in water, meaning that only a fraction of the acid molecules break apart into ions.

Acids have the ability to turn blue litmus paper red, but they do not have any effect on red litmus paper. Red litmus paper remains red in the presence of acids, indicating that it is not affected by them. Therefore, the correct answer is "does not have any effect on it."

The statement "Blue litmus paper turns red in basic solution" is incorrect because blue litmus paper actually turns red in acidic solutions, not basic solutions. Blue litmus paper remains blue or does not change color in basic solutions.

Litmus is an indicator used to test the acidity or alkalinity of a solution. It is not used to test the strength of the solution, but rather to determine its pH level. The color change of litmus paper indicates whether the solution is acidic (turning red) or basic (turning blue). Therefore, the statement that litmus is used to test the strength of an acidic or basic solution is incorrect.

Indicators are substances that are added to acids or bases to determine their nature based on the color change they undergo. These indicators can be natural or synthetic compounds that exhibit different colors in acidic or basic solutions. By observing the color change, one can identify the pH level of the solution being tested. Therefore, indicators are used to indicate the nature of substances being tested by changing color in the presence of acids or bases.