Question

Consider the following properties: I) The red color of rubies is due to the presence of chromium ions. II) Objects made of silver become tarnished. III) The boiling point of ethanol is 78◦C. Which is/are chemical?
(A) II only
(B) II and III only
(C) I only
(D) I and II only
(E) III only
(F) I, II and III
(G) None of these
(H) I and III only

Answer 1

Answer:

Only II) is correct

Explanation:

I) The red color of the rubies is a physical property of its own structure (wich contains  chromium ions)

II)Objects made of silver become tarnished not by a physical property, but as the result of a chemical reaction on the surface of the object made of silver in combination with the sulfur in the air

$2Ag_{(s)}+S\rightarrow Ag_{2}S$

This changes the color of the object to black, (similar to the iron oxidation)

iii)Boiling is a physical change where a liquid substance absorbs heat in some way (e.g. a flame) and becomes a gas