The non-metal A is an important constituent of our food and most of the fuels around us. A forms two oxides B and C. The oxide B is poisonous whereas oxide C causes global warming.

(a) Identify A, B and C

(b) To which group of periodic table does A belong?

(c) Name another element which is placed in the same group as A.

Find the neutral atom in the periodic table which has the same number of electrons as K+ and Cl-. What is this number?

Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electron shells but different number of electrons in their outermost shells. It was found that elements A and G combine to form an ionic compound. This ionic compound is added in a small amount to almost all vegetables and dishes during cooking. Oxides of elements A and B are basic in nature while those of elements E and F are acidic. The oxide of element D is, However, almost neutral. Based on the above information, answer the following questions:

(a) To which group or period of the periodic table do these elements belongs?

(b) What would be the nature of compound formed by a combination of elements B and F?

(c) Which two of these elements could definitely be metals?

(d) Which one of the eight elements is most likely to be found in gaseous state at room temperature?

(e) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively, write the formula of the compound formed by the combination of C and G.

Write the names and symbols of two very reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure, how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.

A non-metal X which is the largest constituent of air combines with hydrogen when heated in the presence of iron as catalyst to form a gas Y. When gas Y is treated with sulphuric acid, it forms a compound Z which is used as a chemical fertilizer.

(a) What are X, Y and Z?

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

(c) Name the period of periodic table in which X is placed.

(d) Which element is placed just before X in the period?

(e) Which element is placed just after X in the period?