An element X combines with oxygen to form an oxide XO. This oxide is electrically conducting.

(a) How many electrons would be there in the outermost shell of the element X?

(b) To which group of the periodic table does the element X belong?

(c) Write the formula of the compound formed when X reacts with chlorine.

An element X has mass number 40 and contains 21 neutrons in its atom. To which group of the periodic table does it belongs?

The element X forms a compound X₂Y. Suggest an element that Y might be and give reasons for your choice.

An element A has an atomic number of 6. Another element B has 17 electrons in its one neutral atom.

(a) In which groups of the periodic table would you expect to find these elements?

(b) What type of bond is formed between A and B?

(c) Suggest a formula of the compound formed between A and B.

The elements A, B, C and D belong to groups 1, 2, 14 and 17 respectively of the periodic table. Which of the following pairs of elements would produce a covalent bond?

(i) A and D

(ii) C and D

(iii)A and B

(iv)B and C

(v)A and C