Question

Read the statements (I-IV) given below and select the correct statements.

I. Waste water from industries often contains non-toxic substances such as heavy metals
II. Heavy metals have a relatively high density (> 5 g/cm³)
III. Mercury, cadmium, copper, lead and sodium are all heavy metals
IV. Accumulation of lead in various organs can cause cancer in humans

• A. I, II and IV
• B. II and IV
• C. I and III
• D. Only II

Answer 1

The correct option is B II and IV

Wastewater from industries such as petroleum, paper manufacturing, metal extraction and processing, chemical manufacturing etc., normally contain heavy toxic metals.

Heavy metals are defined as metallic elements that have a relatively high density (> 5 g/cm3). Examples of heavy metals include mercury (Hg), cadmium (Cd), copper (Cu) and lead (Pb).

Sodium is considered as a lighter metal. The first seven metals in the periodic table are lithium, beryllium, sodium, magnesium, aluminium, potassium and calcium. They are collectively called the “lightest metals”.

Heavy metals are quite toxic and accumulation of lead in various organs induces adverse effects that can cause disorders in the nervous system, Alzheimer’s disease and cancer in humans.