Everyday Science

Corona disease, caused by the coronavirus, is an infectious disease because it spreads from person to person through respiratory droplets.

Milk is composed mostly of water, typically around 87%, which makes option C the correct answer. This high water content is why milk is considered a good source of hydration.

Among the given liquids, mercury is the best conductor of heat due to its metallic nature, whereas water, ether, and alcohol have much lower thermal conductivity.

The Solar System has eight recognized planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Therefore, the correct answer is 8.

Graphite is commonly used as a dry lubricant due to its layered structure, which allows layers to slide over each other easily. Silica, diamond, and iron oxide are not typically used as lubricants.

Nicolaus Copernicus proposed the heliocentric model, demonstrating that the Earth is not the center of the universe, replacing the earlier geocentric model supported by Aristotle.

One gross is a unit of quantity equal to 12 dozen, which is 144 items. Therefore, option C (12 Dozen) is correct.

Radiations are harmful primarily because they alter body tissues at the cellular level, which can lead to various health issues including cancer. While radiation can cause skin cancer, the broader and more accurate harm is the alteration of body tissues.

Vitamin D is chemically known as Calciferol. Retinol is vitamin A, and Tocopherol is vitamin E, so option B is correct.

Adding sugar to water causes boiling point elevation because sugar molecules disrupt the formation of vapor, requiring a higher temperature to boil the solution.