Explanation

Aluminium has a valency of 3 because it loses three electrons to achieve a stable electron configuration.

Its atomic number is 13.

Its electron configuration is 2, 8, 3.

This means it donates three electrons to form Al³⁺ ions.

Explanation

Explanation

Sublimation is the process where a solid directly changes into gas without becoming liquid.

Dry ice (solid CO₂) undergoes sublimation at room temperature.

Explanation

Sand is primarily composed of silicon dioxide (SiO₂), formed when silicon and oxygen combine.

It is a common natural material found in deserts, beaches, and riverbeds.

Explanation

NaCl (sodium chloride) is a compound.

Because it consists of two different elements (sodium and chlorine) chemically bonded.

Explanation

Fractional distillation separates liquids based on differences in their boiling points.

It is commonly used for separating components in crude oil and alcohol purification.

Explanation

Carbon dioxide, methane, and chlorofluorocarbons (CFS) are all significant air pollutants.

They contribute to global warming, ozone depletion, and air quality deterioration.

Explanation

Nitrogen makes up about 78% of Earth's atmosphere,

It is the most abundant gas.

It is essential for plant growth as.

It is a key component of proteins and DNA.

Nitrogen is the chemical element with the symbol N and atomic number 7.

It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772.

Explanation

Explanation