Explanation

Oxygen constitutes about 21%, or more precisely 20.95%, of the Earth's atmosphere by volume

Present about one-fifth of the air.

Supports respiration.

Needed for combustion.

Maintains balance in the atmosphere.

Explanation

Ethnology is the branch of science that deals with the study of races, cultures, and ethnic groups of humans.

The study of human races, particularly their physical characteristics, origins, and distribution

Explanation

An ornithologist is someone who studies ornithology the branch of science devoted to birds.

Ornithology means پرندوں کا مطالحہ

ND5-5-2023

Explanation

An anemometer is an instrument that measures wind speed.

This type of anemometer has a spinning wheel.

Additional Information:

A hygrometer is an instrument used to measure humidity

A salinometer is used to measure the salinity

A bolometer is used to measure the power of incident electromagnetic radiation

A barometer is used to measure air pressure in certain environment.

Explanation

A dentist diagnoses and treats tooth decay, cavities, and other dental problems.

Caries refers to tooth decay or cavities caused by bacteria.

It affects enamel and dentin of the teeth.

Early treatment prevents pain, infection, and tooth loss.

The specialist for oral health issues should be consulted.