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

An element X is in group 2 of the periodic table:

(a) What will be the formula of its chloride?

(b) What will be the formula of its oxide?

An element Y is in second period and group 16 of the periodic table:

(i) Is it a metal or non-metal?

(ii) What is the number of valence electrons in its atom?

(iii) What is its valency?

(iv) What is the name of the element?

(v) What will be the formula of the compound formed by Y with sodium?

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

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.