The atomic number of the element unnilennium is :

Solution

Chemistry ma’am · 2 steps

Break the name into its digit roots, read them left to right, and the number writes itself.

1. IUPAC digit roots. Each digit has a root: 0 nil, 1 un, 2 bi, 3 tri, 4 quad, 5 pent, 6 hex, 7 sept, 8 oct, 9 enn. The roots are joined in the order of the digits, and the name ends in "ium".

   Part of the name	Digit
   un	1
   nil	0
   enn	9
   ium	ending, no digit

2. So. Un-nil-enn-ium reads as 1, 0, 9, so the atomic number is 109, option (a). Today this element is named meitnerium, Mt.

The idea to keep. For any temporary IUPAC name, split it into digit roots and read them in order. "nil" is 0 and "enn" is 9, and those two are the ones students mix up most.

Answer from the NTA final answer key. Solution by PrepWiser.