एक निश्चित अंतराल के बाद तत्वों के गुणों की आवर्ती पुनरावृत्ति को क्या कहा जाता है?

The correct order of increasing metallic character of Na, Be, P, Mg and Si is:

Which of the following is the correct order of increasing atomic radii for nitrogen, oxygen, and fluorine?

Which of the following represents the correct increasing order of atomic radii for the elements fluorine (F), oxygen (O), and nitrogen (N)?