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

What is the common oxidation state of scandium? (At. No. of Sc = 21)

What is the oxidation state exhibited by actinium?

Which of the following statements is incorrect?

Which of the following metal does not form a coloured salt?

Choose the correct statement.

Which of the following statement is correct?

Mild steel is used in construction.