1.
What are the primary raw materials used to make litmus paper?
Correct Answer
D. All of the above
Explanation
The primary raw materials used to make litmus paper are wood cellulose, lichens, and adjunct compounds. Wood cellulose is derived from trees and is used as a base material for the paper. Lichens, specifically Roccella tinctoria, are used to extract a dye called litmus, which gives the paper its characteristic color-changing properties. Adjunct compounds may be added to enhance the durability or performance of the litmus paper. Therefore, all of the above options are correct as they represent the primary raw materials used in the production of litmus paper.
2.
Who used litmus for the first time?
Correct Answer
A. Arnaldus de Villa Nova
Explanation
Arnaldus de Villa Nova is credited with being the first person to use litmus. Litmus is a natural dye obtained from lichens and is commonly used as an indicator in chemistry to determine whether a substance is acidic or basic. Arnaldus de Villa Nova, a 13th-century alchemist and physician, is believed to have discovered the properties of litmus and used it in his experiments and observations. His contribution to the field of chemistry and the development of indicators like litmus paved the way for further advancements in the study of acids and bases.
3.
Litmus dye is obtained from
Correct Answer
A. Lichens
Explanation
Litmus dye is obtained from lichens. Lichens are composite organisms that consist of a symbiotic relationship between a fungus and an alga or cyanobacterium. They are known to produce various secondary metabolites, including dyes. Litmus dye is one such dye that is extracted from certain species of lichens. It is commonly used as a pH indicator in laboratories and is red under acidic conditions and blue under alkaline conditions. Therefore, the correct answer is lichens.
4.
What is purple litmus paper considered?
Correct Answer
C. Neutral
Explanation
Purple litmus paper indicates the solution is neutral or close to neutral. Litmus paper is a common indicator used in chemistry to determine the pH level of a solution. It turns blue in the presence of bases and red in the presence of acids. However, purple litmus paper does not show any color change, indicating that it is not affected by either acidic or basic substances, hence considered neutral.
5.
What color is litmus paper initially?
Correct Answer
D. Both A and B
Explanation
Litmus paper is initially red in color. However, when it comes into contact with an acidic solution, it turns red. On the other hand, when it comes into contact with a basic solution, it turns blue. Therefore, the correct answer is "Both A and B" because litmus paper can be initially red or blue depending on the solution it is exposed to.
6.
What are the limitations of a litmus paper?
Correct Answer
D. Both A and B
Explanation
The correct answer is "Both A and B". This means that the limitations of a litmus paper are that it does not tell how strongly acidic or basic a solution is and it does not provide a numerical pH value.
7.
What is an alternative to the litmus test?
Correct Answer
A. Red cabbage juice
Explanation
An alternative to the litmus test is red cabbage juice. Red cabbage juice can be used as a natural pH indicator, just like litmus paper. It changes color depending on the acidity or alkalinity of a solution. This makes it a suitable substitute for litmus paper in certain experiments or tests to determine the pH level of a substance.
8.
What is yellow litmus paper commonly used for?
Correct Answer
B. To determine whether a substance is acidic or basic.
Explanation
Yellow litmus paper is commonly used to determine whether a substance is acidic or basic. Litmus paper is a pH indicator that changes color in the presence of an acid or a base. When yellow litmus paper is exposed to an acidic substance, it remains yellow or turns red. On the other hand, when it comes into contact with a basic substance, it turns blue. Therefore, yellow litmus paper can be used as a simple and quick method to determine the acidity or basicity of a substance.
9.
When can we say a given solution is acidic?
Correct Answer
B. If purple or blue-colored litmus paper turns red.
Explanation
A given solution can be said to be acidic if purple or blue-colored litmus paper turns red. This is because litmus paper is an indicator that changes color in the presence of acids or bases. In this case, the change from purple or blue to red indicates that the solution has acidic properties.
10.
What does it indicate if the blue litmus paper does not change its color?
Correct Answer
B. The sample is basic.
Explanation
If the blue litmus paper does not change its color, it indicates that the sample is basic. Blue litmus paper is used to test for acidity or basicity of a substance. If the blue litmus paper remains blue, it means that the substance is not acidic and therefore must be basic.