Choose the singular form of the noun given below:
Radii
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Radius
Singular of nouns ending in -i (from Latin):
Some nouns from Latin end in -us in the singular and -i in the plural. So radii → radius. A radius is a straight line from the centre of a circle to its edge. Radium is a different word: a metal that gives off rays.