Question

Abundance of element in human body in descending order are
A) O,C,H,N
B) H,C,O,N
C) C,O,H,N
D) H,O,C,N

Answer 1

Our body is mainly composed of water and other biomolecules like proteins, fats, DNA, carbohydrates. These biomolecules are majorly made up of carbon, hydrogen, nitrogen and oxygen.

Complete answer:
To answer this question, we must know about the composition of elements present in our body.
Our body is mainly made up of 4 atoms- carbon, nitrogen, hydrogen and oxygen. 99% of our body mass is due to these atoms.

i) Oxygen- It is the main atom which helps in supporting life. Oxygen is the chief constituent of water which our body is made up of. Our body has around 65%.
ii) Carbon- Our body is made up of organic molecules. Carbon forms the basic backbone of organic molecules like carbohydrates, proteins, fats etc. Around 18.5% of our body is made up of carbon.
iii) Hydrogen- Hydrogen is the chief constituent of water. It is also present in the biomolecules like carbohydrate, fat, proteins etc.
iv) Nitrogen – Around 1% of our body is made up of nitrogen. Nitrogen is present in the DNA, proteins and other amino acids.

Thus the correct answer is option (A). The molecules in descending order are O, C, H, N.

Note: Apart from these four elements, calcium and phosphorus are also the main elements present in our body. Calcium and phosphorus are the main constituents of bone. Potassium, sodium, chlorine, sulphur and magnesium are other important elements which constitute around 0.85%. There are other trace elements like molybdenum, fluorine, zinc, silicon, bromine, lead etc. All these elements are necessary for life.