Physical And Chemical Changes Quiz For Grade 5

Explanation
Cooking an egg involves breaking down the proteins in the egg through the application of heat. This process, known as denaturation, results in the irreversible change of the egg's texture and structure. The proteins in the egg undergo chemical reactions, leading to the formation of new compounds, such as the Maillard browning reaction that gives cooked eggs their golden color. Therefore, cooking an egg is considered a chemical change rather than a physical change.

Explanation
Shredding paper is considered a physical change because it does not alter the chemical composition of the paper. The paper is simply being physically broken down into smaller pieces, but its chemical properties remain the same. In a chemical change, new substances are formed with different chemical properties. Since shredding paper does not result in the formation of new substances, it is classified as a physical change.

Explanation
In a chemical change, a new substance is formed. This means that the original substance undergoes a transformation at the molecular level, resulting in the formation of one or more new substances with different properties. This can involve the breaking and forming of chemical bonds, rearrangement of atoms, or change in the chemical composition of the substance. In contrast, a physical change does not result in the formation of a new substance and only involves a change in the physical properties of the substance, such as shape, size, or state of matter.

Explanation
Microwaving a bowl of soup is a physical change because it does not involve any chemical reactions. The process of microwaving simply applies heat to the soup, causing the molecules to move faster and increase in temperature. This change in temperature may cause the soup to boil or evaporate, but it does not alter the chemical composition of the soup. Therefore, it is considered a physical change.

Explanation
Water changing state in the water cycle is considered a physical change because it involves a change in the physical properties of water without any alteration in its chemical composition. In the water cycle, water can change from a liquid state (such as rain or condensation) to a gaseous state (such as evaporation or transpiration) or a solid state (such as snow or ice). These changes are reversible, and the water molecules remain the same throughout the process. Therefore, the change is classified as a physical change rather than a chemical change.

Explanation
The given statement describes a physical change because it involves the alteration of the car's appearance through the creation of a dent. Physical changes do not involve the formation of new substances, but rather a change in the physical properties of a material. In this case, the car's structure is changed, but the composition of the material remains the same.

Explanation
The cutting of wood is a physical change because it does not alter the chemical composition of the wood. The wood is simply being physically altered in shape or size, but the molecules and atoms that make up the wood remain the same. No new substances are formed during the cutting process, which is why it is considered a physical change.

Explanation
The evaporation of camphor is a physical change because it does not result in the formation of any new substances. During evaporation, the camphor molecules gain enough energy to break their intermolecular bonds and escape into the air as a gas. However, the chemical composition of camphor remains the same throughout this process. Therefore, it is considered a physical change rather than a chemical change.

Explanation
Milk turning sour is a chemical change. This is because the souring of milk is caused by the action of bacteria on lactose, a sugar present in milk. The bacteria produce lactic acid as a byproduct, which gives the milk a sour taste and changes its composition. This change is irreversible and involves a chemical reaction, making it a chemical change rather than a physical change.

Explanation
Tearing of paper is a physical change because it does not alter the chemical composition of the paper. The paper remains the same substance even after it is torn into smaller pieces. It is only the physical appearance and shape of the paper that changes. No new substances are formed, and the tearing can be reversed by simply taping or gluing the pieces back together.

Explanation
When acid rain comes into contact with rocks, it reacts with the minerals present in the rocks, causing a chemical change. This reaction leads to the breakdown and dissolution of the minerals, resulting in the wearing away or erosion of the rock surface. This process is a chemical change because the composition of the rock is altered due to the reaction with the acid rain.

Explanation
Mixing paint colors is a physical change because it does not result in a new substance being formed. In this process, the individual paint colors are combined, but their chemical composition remains the same. The molecules of the paint colors do not undergo any chemical reactions or transformations. Instead, they are simply physically mixed together, resulting in a new color or shade. Therefore, mixing paint colors is classified as a physical change rather than a chemical change.

Explanation
Fireflies produce light through a chemical reaction called bioluminescence. This process involves a series of chemical reactions within the firefly's body, where a molecule called luciferin reacts with an enzyme called luciferase in the presence of oxygen to produce light. This chemical reaction is a characteristic of fireflies and is not reversible, indicating that it is a chemical change rather than a physical change.

Explanation
Rotting of fruits is a chemical change because it involves the breakdown of organic matter (fruits) by microorganisms such as bacteria and fungi. This process, known as decomposition, results in the formation of new substances such as gases (e.g. methane, carbon dioxide), liquids (e.g. organic acids), and solids (e.g. mold). These changes cannot be reversed and involve the breaking and forming of chemical bonds, indicating a chemical reaction rather than a mere rearrangement of particles (physical change).