Why is there an increase in the atomic radius of transition elements at the end of the period?

Which of the following has the highest atomic number?

All actinoids are diamagnetic in nature.

Choose the correct statement.

What happens to the atomic size of the lanthanides with increase in atomic number?

Mild steel is used in construction.

Which is the most stable oxidation state of actinoids?

Which compound is used in Ultra-violet calibration?