Which of the following is an element with atomic number 30 as per the modern periodic table?
- A.Ni
- B.Fe
- C.Zn
- D.Co
Show answer
Correct answer: C. Zn
Explanation
The correct answer is C, Zn. Zinc has atomic number 30, meaning every zinc atom has 30 protons in its nucleus. It is the last element of the first transition series in period 4 of the modern periodic table, with the electronic configuration [Ar] 3d10 4s2, and it is placed in group 12. Zinc is a bluish-white metal used to galvanise iron against rust, to make brass with copper, and in dry cells. All four options are neighbours in the same period, which is why paper setters like this question: iron is 26, cobalt 27, nickel 28, copper 29 and zinc 30. A is wrong because Ni, nickel, has atomic number 28. B is wrong because Fe, iron, has atomic number 26. D is wrong because Co, cobalt, has atomic number 27. Exam tip: remember the run Fe 26, Co 27, Ni 28, Cu 29, Zn 30.