Question

Which property can be used to know purity of a substance?

• A. Mp
• B. Bp
• C. magnetic
• D. none

Answer 1

Answer: (A), (B)

Mp, Bp

Answer 2

Melting Point (Mp): For solid substances, purity is often checked by determining their melting point. A pure crystalline solid has a sharp and definite melting point. The presence of impurities usually lowers the melting point and broadens the melting range.

Boiling Point (Bp): For liquid substances, purity is often checked by determining their boiling point. A pure liquid has a sharp and definite boiling point at a given pressure. The presence of non-volatile impurities usually elevates the boiling point.

Magnetic property: Magnetic properties are specific to certain types of substances and are not a general criterion for assessing the purity of all substances. For instance, the purity of water or organic compounds cannot be reliably checked using magnetic properties.

Therefore, both melting point and boiling point are reliable physical properties used to determine the purity of a substance.