This question refers to the elements of the Periodic Table with atomic numbers from 3 to 18. Some of the elements are shown by letters, but the letters are not the usual symbols of the elements.

Which of these :

(a) is the most electronegative element ?

(b) is a halogen ?

(c) is an alkali metal ?

(d) is an element with valency 4 ?

(e) have least Ionisation Energy.

(f) have least atomic size in period 3.

A group of elements in the Periodic Table are given below (boron is the first member of the group and Thallium is the last).

Boron, Aluminium, Gallium, Indium, Thallium

Answer the following questions in relation to the above group of elements :

(a) Which element has the most metallic character ?

(b) Which element would be expected to have the highest electronegativity ?

(c) If the electronic configuration of aluminium is 2, 8, 3, how many electrons are there in the outer shell of thallium ?

(d) The atomic number of boron is 5. Write the chemical formula of the compound formed when boron reacts with chlorine.

(e) Will the elements in the group to the right of this boron group be more metallic or less metallic in character ? Justify your answer.

Which of the following properties does not match with the elements of the halogen family ?

1. They have seven electrons in their valence shell.
2. They are highly reactive chemically.
3. They are metallic in nature.
4. They are diatomic in their molecular form.

With reference to the variation of properties in the Periodic Table, which of the following is generally true?

1. Atomic size increases from left to right across a period.
2. Ionization potential increases from left to right across a period.
3. Electron affinity increases going down a group.
4. Electronegativity increases going down a group.