Explanation

Joseph Priestley discovered laughing gas (nitrous oxide) in 1772.

It was later studied for its anesthetic properties.

Explanation

Calcium is crucial for:

• Building and maintaining strong bones and teeth
• Muscle function and contraction
• Nerve function and transmission
• Blood clotting and wound healing

Explanation

The energy stored in coal is classified as chemical energy.

It is released during combustion when the chemical bonds in the coal are broken.

This energy is harnessed for heating and electricity generation.

Explanation

Chlorine atoms in Chlorofluorocarbons (CFCs) are primarily responsible for the depletion of the ozone layer. 

Explanation

Geologists are scientists who study a planet's solid features, like soil, rocks, and minerals.

Explanation

Paleontology is the branch of science concerned with the study of fossils and the history of life on Earth

Fossils are the remains of plants, animals, fungi, bacteria, and single-celled living things

that have been replaced by rock material or impressions of organisms preserved in rock.

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Explanation

• When light travels from a denser to a rarer medium, it bends away from the normal due to refraction.
• The production of an image by or as if by a mirror is called reflection.

Explanation

• An ecosystem includes all the living components (biotic factors) like plants, animals, and microorganisms, and non-living components (abiotic factors).
• Like soil, water, air, and sunlight, interacting with each other.

Explanation

Explanation

The annual number of live births per 1,000 people is called the Crude Birth rate

ہر ایک ہزار افراد کی سالانہ پیدائش کی شرح کو خام پیدائش کی شرح کہا جاتا ہے۔

the annual number of deaths per 1,000 people is called the Crude death rate

ہر ایک ہزار افراد کی سالانہ اموات کو خام اموات کی شرح کہا جاتا ہے۔