निम्नलिखित में से कौन सा तत्व पृथ्वी की भूपर्पटी (क्रस्ट) में प्राकृतिक रूप से पाया जाने वाला सबसे दुर्लभ तत्व 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)?

Which of the following elements does NOT belong to the 2nd period of the periodic table?

An element with atomic number 14 is hard, forms an acidic oxide, and forms covalent halides. To which category does this element belong?

The modern periodic table is based on which of the following properties of elements?

The correct order of magnitude of electron gain enthalpy for halogens is:

The correct order of ionic radii for the following ions is: O2-, F-, Na+, Mg2+