Question

Which of the following non-metal is non-lustrous?
(a) Diamond
(b) Iodine
(c) Diamond and iodine
(d) None of the above

Answer 1

Hint: A metal or a non-metal is said to be lustrous when it has an intrinsic shining/lustre. Similarly, a non-lustrous metal or a non metal would be the one which does not have such shining or lustre.

Complete Step by Step Solution:
We first need to identify whether the given elements are metal or non-metal. Then we can talk about their lustrous property.
● Diamond is essentially carbon. And as we know that carbon is a solid non-metal element. Also, carbon can exist in different forms on earth. Diamond is one form of carbon which is formed at extreme thermodynamic conditions. And well as we all know that Diamond is actually the hardest natural substance on Earth. So, diamond is essentially non-metal.
● Iodine is the most electropositive halogen and also the least reactive one, although it is found to form compounds with many other elements. You see, iodine is a non-metal, has dark-gray texture. It is evident through different discoveries that iodine is a lustrous non-metal.
● On the other hand, Diamond has a very bright lustre, so much that it has the highest non-metallic lustre.
● So, we can safely say that both the iodine and diamond which is essentially a non-metal form of carbon are non-metals. Moreover, it could be concluded that both of them are lustrous.
● Hence, the correct answer we are looking for is both iodine and diamond are lustrous non-metals. So, the answer is D.

Note: Diamond as discussed has the highest non-metallic lustre; this is also known as “adamantine”. Diamonds' high amount of lustre gives the diamond the ability to reflect a large amount of light that strikes their surface. They exhibit the phenomenon called the Total Internal Reflection.