Explanation

NO₂ is a reddish-brown gas that gives photochemical smog its characteristic brownish color.

It is formed by the reaction of NO with oxygen in sunlight.

It is a major pollutant in urban smog.

Explanation

Raney nickel is prepared by treating a nickel-aluminum (Ni-Al) alloy with concentrated NaOH.

This process removes aluminum, leaving behind porous nickel, which acts as an excellent hydrogenation catalyst.

Explanation

Water (H₂O) is composed of 2 hydrogen atoms (1g each) and 1 oxygen atom (16g) → total molar mass = 18g.

Percentage of oxygen = (16/18) × 100 = 88.8% by mass.

Explanation

Plastic is primarily made from petrochemicals, including oil and natural gas.

They are processed to create synthetic polymers used in manufacturing.

Explanation

Surfactants reduce the surface tension of water, which is the energy required to create a surface between water and air.

By reducing surface tension, surfactants make it easier for water to spread and penetrate surfaces, which is important for cleaning and other applications.

Explanation

• When the pressure on a gas increases, the molecules are forced closer together, resulting in a higher density.
• This is because the volume of the gas decreases as the pressure increases, causing the molecules to be more concentrated.

Explanation

• Magnesium (Mg) is an alkaline earth metal that loses two electrons from its outer shell to form a divalent cation (Mg²⁺).
• This means that it typically loses two electrons to form compounds, resulting in a valency of +2.

Explanation

• Atomic radius decreases along a period as you move from left to right.
• This is because the number of protons in the nucleus increases, which pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.

Explanation

The reaction where larger hydrocarbons (like C₈H₁₈) break into smaller ones (like C₃H₆ and fragments) is called cracking.

Cracking is commonly used in the petroleum industry to produce smaller, more useful hydrocarbons such as alkenes and gasoline.

Explanation

Laughing gas is the common name for nitrous oxide (N₂O), a colorless gas with a slightly sweet smell.

It acts as a mild anesthetic and analgesic.

It is often used in dentistry and surgery.