Explanation

 Alkali metals are found in Group 1 of the periodic table.

Potassium (K) is located in Group 1, making it an alkali metal. 

Explanation

 Sir William Ramsay, a Scottish chemist, is credited with the discovery of the noble gases.

He first discovered argon and later found neon, krypton, and xenon. 

Explanation

Explanation

Glass, iron, plastic, and paper are typically considered non-recyclable domestic waste;

They are generally accepted for recycling in most communities

Explanation

 XeF2 has two fluorine atoms bonded to a central xenon atom, with the lone pairs on the xenon arranged in an equatorial plane.

This results in a linear structure where the fluorine atoms are directly opposite each other along a straight line. 

Explanation

The –SH group is present in thiols. 

A thiol is a functional group where a sulfur atom is bonded to a hydrogen atom.

The -SH group is analogous to the -OH group in alcohols, except that sulfur replaces oxygen. 

Explanation

 Tetraethyl lead (TEL) was historically added to gasoline to increase its octane rating and reduce knocking, but due to its environmental concerns, it has largely been phased out. 

Explanation

 Knocking causes incomplete combustion and inefficient engine performance, which reduces the efficiency of an engine.

Explanation

PVC (Polyvinyl chloride) is formed by addition polymerization of vinyl chloride.

Polystyrene is also formed by addition polymerization of styrene (C₆H₅CH=CH₂).

Explanation

Benzene is an aromatic compound with a stable delocalized π-electron system.

It resists addition reactions (which would disrupt aromaticity) and typically undergoes substitution reactions instead.