Question

What is the atomic number of first post actinoid element ?

• A. \(101\)
• B. \(108\)
• C. \(104\)
• D. \(110\)

Hint:

Actinoids end at lawrencium (103), so the next element is the first post actinoid.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The actinoid series runs from actinium (89) to lawrencium (103). The element after Lr is the first post actinoid (a 6d series element).

Step 2: Identify:
The next atomic number is 104, rutherfordium (Rf). It sits below hafnium in group 4. The values 101 (Md) belongs to actinoids, while 108 and 110 are further along the 6d series.

Final Answer:
The first post actinoid element has atomic number 104, option (C). \[ \boxed{104} \]