The elements fo one short period of the periodic table are given below in order from left to right:
Li, Be, B,C O F, Ne

i) To which period do these elements belong?

ii) One element of this period is missing which is the missing element and where should it be placed.

iii) Which one of the element in this period shows the property of catenation? 

iv) Place the three elements fluorine, beryllium and nitrogen in the order of increasing electronegativity. 

v) Which one of the above elements belongs to the halogen series?

What is a lone pair of electrons?

Draw an electron dot diagram of a hydronium ion and label the lone pair of electrons.

Name a neutral covalent molecule which contains one lone pair of electrons.

Choose the correct answer from the choices A, B,C,and D:

The property which is characteristic of an electrovalent compound is that:

• It is easily vaporise

• It has a high melting point

• It is weak electrolyte

• It often exist as a liquid