निम्नलिखित तत्वों में से कौन सा सामान्य परिस्थितियों में विशिष्ट संरचनात्मक अपरूप (एलोट्रोप) नहीं बनाता 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)?