Explanation

An alkyl group is formed by removing a hydrogen atom from an alkane, and since the hydrogen atom is removed with one bonding electron, the resulting group has an unpaired electron, making it a radical. 

Explanation

In the 3d series of the periodic table, melting and boiling points generally increase up to the middle,

Reaching a peak around elements like Chromium (Cr), and then decreasing towards the end of the series, with Zinc (Zn) having the lowest melting point. 

Explanation

Astatine is considered the rarest naturally occurring element on Earth, making it the "rare halogen" among the group which includes fluorine, chlorine, bromine, and iodine. 

Explanation

Macromolecules are large, complex molecules composed of smaller repeating units called monomers.

Thyroxin, haemoglobin, and insulin are all proteins, which are macromolecules made up of chains of amino acids.

Maltose, on the other hand, is a disaccharide, meaning it's made up of only two sugar units (glucose) and is not considered a true macromolecule. 

Explanation

Lactic acid is not an amino acid; glutamic acid, aspartic acid, and glycine are all amino acids. 

Lactic acid:

This is an organic compound involved in energy metabolism, but it does not have the characteristic structure of an amino acid. 

Explanation

The chemical formula for palmitic acid is C₁₆H₃₂O₂.

It is also known as hexadecanoic acid.

Palmitic acid is a saturated fatty acid, meaning it contains only single bonds between carbon atoms. 

Explanation

A fatty acid is a carboxylic acid with a long aliphatic chain.

Phthalic acid has a benzene ring structure, which is not characteristic of fatty acids

Explanation

Iodine is solid due to its high polarizability. 

Iodine is a solid at room temperature due to the strong intermolecular forces present between its molecules, specifically London dispersion forces

These forces arise from the large size and high polarizability of iodine atoms.

Larger atoms like iodine have more electrons, which are easier to distort, leading to stronger attractive forces between molecules.

This allows iodine molecules to stick together in a solid state

Explanation

Fluorine, being the smallest halogen, has the weakest intermolecular forces and therefore the lowest boiling point. 

Explanation

Oxygen ions (O²⁻) are highly reactive and readily combine with other elements to form more stable compounds

In aqueous solutions, they readily react with water to form hydroxide ions (OH⁻) and oxygen gas (O₂), effectively neutralizing their existence as free O²⁻ ions.

This makes it extremely difficult for O²⁻ to exist independently in a solution.