Which of the following element belongs to the first transition series of the periodic table?

Which of the following statement is correct?

Which is the most stable oxidation state of actinoids?

Which of the following iswhy the atomic radii of the second and third transition series are almost same?

The decrease in atomic size of the d-block elements in a series is small after midway.

Where does the last electron of d-block element go?

Actinoids are mostly attacked by which acid?

Which of the following is not a property of a transition metal?