Science

Leather is primarily composed of collagen, a structural protein found in animal skin. Collagen provides the strength and flexibility characteristic of leather.

Venus has the slowest rotation period of all the planets in the solar system, taking about 243 Earth days to complete one rotation, which is slower than Mars, Jupiter, or any other planet.

Mercury is the only metallic element that is liquid at room temperature. Since it is not listed among the options, the correct choice is 'None of these.'

Vitamin K is the vitamin responsible for blood clotting, and since it is not listed among the options, the correct choice is 'None of these.' Vitamins A, D, and C do not play a direct role in blood clotting.

Synthetic vinegar is primarily composed of acetic acid, which is the chemical responsible for vinegar's characteristic smell and taste. Therefore, the chemical name of synthetic vinegar is acetic acid.

Myopia, also known as nearsightedness, is a common eye condition where distant objects appear blurry. It is directly related to the eyes, making option C correct.

An equinox occurs when day and night are approximately equal in length all over the Earth. This happens twice a year, marking the start of spring and autumn.

Saturn is the second largest planet in our solar system after Jupiter. Uranus and Neptune are smaller than Saturn.

The ozone layer in the Earth's stratosphere absorbs most of the Sun's harmful ultraviolet (UV) radiation, protecting living organisms on Earth from its damaging effects.

Alzheimer's disease primarily damages nerve cells (neurons) in the brain, leading to memory loss and cognitive decline. It does not affect spleen or liver cells.