Classification ...

The electronic configuration of four elements are :
I. $$[Kr]5s^1$$
II.$$[Rn]5f^{14}6d^{1}7s^2 $$
III.$$[Ar]3d^{10}4s^24p^5$$
IV.$$[Ar]3d^64s^2$$.
Consider the following statements :
I show variable oxidation state
II is a d-block element
The compound formed between I and Ill is covalent
IV shows a single oxidation state
Which statement is True (T) or False (F)?

Which one of the following statements is incorrect?

Electronic configuration of $$Al^{3+}$$ is

The element with electronic configuration (Ar) $$ 3d^{2} 4s^{2} $$  belongs to which block ?

The outermost electron configuration of an element in this is $$2s^2\ 2p^6$$. This represents:

The atom of which of the following elements forms dual closed shell configuration by receiving one electron?

Which of the following will not have $$18$$ electrons?

How many electron are there in chloride ion?

Which of the following statements is not correct for the element having electronic structure $$2,8,8,2$$?