How many allotropes does nitrogen have?

The correct answer is option 1. Zero.

Allotropy is not present in the nitrogen atom. This is owing to its tiny size and strong inter-electronic repulsion, which causes the N - N to become very weak. There are two expected kinds of nitrogen allotropes, but, in theory. Alpha nitrogen, which only occurs below 35.6 K, or a whopping -237.55°C, takes a cubic shape. Between 35.6 K to 63.15 K, beta nitrogen is present. Following that, it melts.