Which one of the following pairs (Metals or Minerals) is not correctly matched?

Correct option is A

The correct answer is: (a) Base metal – Cobalt
Explanation
(a) Base metal – Cobalt → Incorrect
· Cobalt is not classified as a base metal.
· Base metals are inexpensive and commonly used, like copper, zinc, lead, tin.
· Cobalt is a strategic / specialty metal, used in batteries and alloys, not in the base-metal category.
(b) Precious metal – Silver → Correct
· Silver is a well-known precious metal along with gold and platinum.
(c) Non-metallic mineral – Diamond → Correct
· Diamond is a non-metallic mineral, even though it is extremely hard.
(d) Ferro Alloys – Nickel → Correct
· Nickel is used to produce ferro-nickel alloys, used in stainless steel manufacturing.
Additional Information
· Base metals: copper, lead, tin, zinc → widely used and inexpensive.
· Precious metals: gold, silver, platinum → high economic value.
· Ferro alloys: alloys of iron with elements like manganese, silicon, chromium, nickel → used in steel industry.
· Diamonds are formed from pure carbon but remain non-metallic due to their structure.