The maximum number of covalent bonds formed by nitrogen is

The IUPAC name of the compound CH3CH(CH3)CHCH2 is

Ionization energy increases across the period in the periodic table because

Which of the following properties indicate that an element is a metal. It

I. reacts with oxygen to form an acidic oxide
II. forms ionic chlorides
III. has variable oxidation states
IV. displaces hydrogen from dilute HCl

The electron configuration of carbon atom in its excited state is