1.
Which of these is not a characteristic of chemical changes?
Correct Answer
A. It is not easily reversible
Explanation
Chemical changes involve the formation of new substances, which is a characteristic of chemical changes. They are also not easily reversible, meaning it is difficult to revert the substances back to their original form. Catalysts are not always involved in chemical changes, so it is not a characteristic. Therefore, the correct answer is "It is easily reversible."
2.
What is the process of change in substance from solid to gas?
Correct Answer
C. Condensation
Explanation
Condensation is the process of change in substance from a gas to a liquid. In this case, the question is asking for the process of change from a solid to a gas. Therefore, condensation is not the correct answer. The correct answer should be sublimation, which is the process of change from a solid directly to a gas without going through the liquid phase.
3.
Which of these is neutral?
Correct Answer
A. Carbon (II) oxide
Explanation
Carbon (II) oxide is neutral because it has an equal number of positive and negative charges. In this compound, carbon has a +2 charge, and oxygen has a -2 charge. These charges cancel each other out, resulting in a neutral compound.
4.
What element is behind matching sticks?
Correct Answer
B. SulpHur
Explanation
Sulphur is the correct answer because it is the only element among the options that is commonly used to create matches. Sulphur is a key component of the match head, where it helps initiate the combustion reaction when struck against a rough surface. Carbon, Molybdenum, and Manganese do not have a significant role in the creation or function of matches.
5.
Which of these is odd?
Correct Answer
A. Filtration
Explanation
Filtration is the odd one out among the given options because it is the only process that involves the separation of solid particles from a liquid or gas by passing it through a porous medium. Fractional distillation, rusting of metals, and burning of paper are all chemical processes that involve the transformation or reaction of substances.
6.
Which of these is Kipp apparatus needed during its preparation?
Correct Answer
C. Hydrogen sulpHide
Explanation
The Kipp apparatus is needed during the preparation of hydrogen sulphide. The Kipp apparatus is a laboratory device used for generating small volumes of gases. It consists of two chambers, one for the reactants and one for the generated gas. In the case of preparing hydrogen sulphide, the apparatus would be used to react a suitable source of sulphur with a suitable acid, such as hydrochloric acid, to produce hydrogen sulphide gas.
7.
Which of these is not a chemical change?
Correct Answer
B. Mixing of water with salt
Explanation
Mixing of water with salt is not a chemical change because it is a physical change. In this process, the water molecules and salt particles do not undergo any chemical reactions or form new substances. The salt dissolves in water, creating a homogeneous mixture, but the chemical composition of both water and salt remains unchanged.
8.
Which of these is not among the types of reactions?
Correct Answer
D. Irreversible reaction
Explanation
An irreversible reaction is not among the types of reactions. In a reversible reaction, reactants can form products, and products can also react to form reactants. However, in an irreversible reaction, the reaction proceeds only in one direction and cannot be reversed.
9.
Which of these is not a carbon?
Correct Answer
D. Bronze
Explanation
Bronze is not a carbon because it is an alloy composed primarily of copper and tin, with small amounts of other metals. It does not contain carbon as one of its main components. Coke, coal tar, and ammoniacal liquor, on the other hand, are all carbon-based substances. Coke is a solid carbonaceous material derived from coal, coal tar is a thick, black liquid produced during the distillation of coal, and ammoniacal liquor is a solution of ammonia in water, which contains carbon atoms.
10.
Which of these reactions produces heat?
Correct Answer
A. Exothermic reaction
Explanation
Exothermic reactions produce heat as a byproduct. In these reactions, the energy released from the reaction is greater than the energy required to break the bonds of the reactants. This excess energy is released in the form of heat, resulting in an increase in temperature in the surroundings. Examples of exothermic reactions include combustion reactions, such as burning wood or gasoline, where heat is released.