Question

Find the odd one out and explain your choice.

(Hint: valency is not a criterion)

Sulphur, phosphorus, carbon, iodine.

Answer 1

• The criterion that is used to find the odd one out in the given case is Lustre. Metals are lustrous whereas Non-metals are dull.
• Elements such as Sulphur $\left(S\right)$, Phosphorus $\left(P\right)$, Carbon $\left(C\right)$ and Iodine $\left(I\right)$ are all non-metals.
• All the given non-metals are dull except Iodine.
• It is because Iodine has three-dimensional crystal structure which helps it to reflect most of the light falling on it.

The odd one out is Iodine because, being a non-metal it is lustrous.