GENERAL KNOWLEDGE

Detailed explanation-1: -Oxygen is by far the most abundant element in the Earth’s crust, making up 46% of mass-coming up just short of half of the total. Oxygen is a highly reactive element that combines with other elements, forming oxides.

Detailed explanation-2: -The vibrational spectrum of iron, the most abundant element in Earth’s core, at 171 gigapascals. By squeezing iron between two diamond anvils (inset), Caltech researchers reproduced the pressures found in Earth’s core.

Detailed explanation-3: -It is the second most abundant element in the Earth’s geosphere after iron and the most abundant element by mass in the Earth’s crust-at about 47% to 49%. Oxygen makes up about 89% of the world’s oceans, and diatomic oxygen gas constitutes about 20% of the Earth’s atmosphere-second only to nitrogen.