Science Quiz Class 7

Burning of garbage releases harmful pollutants into the air, leading to air pollution. This air pollution can cause respiratory diseases such as lung cancer and asthma.

A switch in an electronic device is used to interrupt the flow of electricity or electric current. Electrical switches are binary devices, they can be either completely off or completely on. In simple English, a switch is an electronic device which is used to break or make the electronic circuit.

Premolars function in the same way as the object shown in the picture. The picture is not provided, but premolars are the teeth located between the canines and molars. They have a flat surface with cusps that are used for grinding and chewing food. Incisors are located at the front of the mouth and are used for biting and cutting, while canines are pointed teeth used for tearing and gripping. Therefore, premolars are the teeth that have a similar function to the object shown in the picture.

Solids, liquids, and gases all exert pressure. In solids, the particles are closely packed together, and they exert pressure on each other. In liquids, the particles are not as closely packed as in solids, but they still exert pressure on the walls of the container they are in. In gases, the particles are far apart and move freely, exerting pressure in all directions. Therefore, all three states of matter exert pressure.

A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding.

The four main parts of flowers are sepals, petals, stamens, and carpels. ... The carpels are female reproductive structures that produce egg cells and protect a developing baby plant, or embryo. The three main parts of a carpel are the stigma, style, and ovary. The stigma is where pollination occurs.

Sulphur dioxide can dissolve in water to form Sulfurous acid(H2SO3). ... sulphurous acid is weackly dibasic acid. sulphur dioxide is a major component of acid rain since it mixes with vapour in the atmosphere reacting to produce H2So4 .

The given correct answer is "To remove pure or harmless components." This is an incorrect reason for separating components of a mixture because the purpose of separation is usually to obtain the pure sample of a substance or to remove undesirable and useless components, not to remove pure or harmless components. Separating pure or harmless components would not serve any practical purpose in most cases.

Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs.

Inhaled air is by volume 78.08% nitrogen, 20.95% oxygen and small amounts of other gasses including argon, carbon dioxide, neon, helium, and hydrogen. The gas exhaled is 4% to 5% by volume of carbon dioxide, about a 100 fold increase over the inhaled amount.