Question

Which of the following is a lustrous non-metal?
a) Chlorine
b) Nitrogen
c) Iodine
d) Fluorine

Answer 1

We must have the knowledge about properties of metals and non-metals of modern periodic table. Also there are certain exceptions in periodic tables with both metals and non-metals which have to be kept in mind while answering.

Complete solution:
Mostly metals and non-metals are the solids found in the modern periodic table which have completely different physical and chemical properties.
At room temperature metals are present in solid state. They have a strong intermolecular force of attraction, thus the interstitial space between the corresponding atoms is too low.
Metals also have luster, high density. They have luster, are good conductors of heat and electricity. So are used in kitchen appliances, household appliances, and electrical appliances. They are also ductile and malleable.
Most of the metals are hard but there are some exceptions, like Sodium ($Na$) and Potassium ($K$) are soft and can be cut with a knife. Metals like Tungsten ( $W$), Iridium ($Ir$) and Titanium ($Ti$) are some of the hardest metals.
Most non-metals are not so hard like metals. They can exist as solids, liquids, and gas at room temperature. They are considered as brittle and thus are not malleable and ductile. They don't have a lustrous outer layer like metals. They don't conduct electricity.
But there are certain exceptions where a nonmetal naming Iodine$(I)$ is lustrous. In the qualitative analysis of iodine, it gives violet vapours.

Hence the correct option is (C).

Additional Information: Sodium ($Na$) and Potassium ($K$) are highly reactive metals as when they come in contact with air they react vigorously and catch fire.so they are kept in kerosene.

Note: Graphite$(C)$which being a non-metal can easily conduct electricity as the different layers of graphite have weak van der waals interaction and one carbon is bonded to three other carbon. Thus one free electron present helps in conducting electricity.