Explanation

Railway tracks are made of steel, which expands in summer heat.

The gaps between rails allow space for this expansion, preventing the tracks from buckling or derailing trains.

Explanation

Cooking gas, also known as liquified petroleum gas (LPG), is a mixture of propane and butane.

It is a flammable mixture of hydrocarbon gases.

Explanation

Hydrogen is the most abundant element in the universe.

it is about 75 percent of its normal matter and was created in the Big Bang.

Additional information:

Oxygen is the most abundant element in the earth`s crust.

Calcium is the most abundant mineral in the human body.

Explanation

72 beats per minute is a good heart rate.

Complete answer:

The resting person usually has a pulse rate between 70 (beats per minute) and 80 (beats per minute).

Your risk of dying from a heart attack is lower if your heart rate is below 80 beats per minute.

A normal resting heart rate ranges from 60 to 100 beats per minute.

Explanation

Graphite is a crystalline form of the element carbon.

It consists of stacked layers of graphene.

Graphite occurs naturally and is the most stable form of carbon under standard conditions.

Explanation

Explanation

The approximate surface temperature of the Sun, also known as the photosphere,

It is around 5,800 Kelvin (5,500 degrees Celsius or 10,000 degrees Fahrenheit).

Explanation

A bee is a flying insect known for pollination and producing honey.

It belongs to the order Hymenoptera, which also includes wasps and ants.

Explanation

The approximate height of Earth's atmosphere is 6,200 miles (10,000 kilometers).

This is the approximate extent of the exosphere, the outermost layer of the atmosphere, which gradually merges with space. 

Explanation

A thermos flask is used to maintain the temperature of liquids, keeping hot things hot and cold things cold for extended periods.

It achieves this by minimizing heat transfer through a combination of insulation and a vacuum.