Heavy metals include all metals with atomic numbers greater than ___:

Correct option is D

Heavy metals are generally considered to include metals with atomic numbers greater than 55, such as lead, mercury, and cadmium.
· These metals have a higher density and are often toxic at elevated concentrations.
Explanation:
· (a) 11 – This would include metals like sodium, which are not considered heavy metals.
· (b) 23 – Metals with atomic numbers greater than 23, like vanadium, are not considered heavy metals by standard definitions.
· (c) 42 – This includes metals like molybdenum, which are not heavy metals.
· (d) 55 – Correct answer. Heavy metals generally have atomic numbers greater than 55, such as lead, mercury, and cadmium.