Three elements A,C and C have successitive atomic number in incresing order .A attains stability when an electorn is added to thee third shell which is the valecne shell .Identify A,B and c and predict the respective elements possessing the maximum ionisation energy oxidizing power reducing power electrons affinity and atomic size

Explanation

To solve the question step by step, we will identify the elements A, B, and C based on the information provided and then predict their respective properties.

### Step 1: Identify the Elements A, B, and C
- **Element A**: The question states that A attains stability when an electron is added to the third shell (valence shell). This indicates that A has 7 valence electrons, placing it in Group 17 (the halogens). The first element in the third period of Group 17 is Chlorine (Cl), which has an atomic number of 17.

- **Element B**: Since A is Chlorine (Cl), the next element in the periodic table (successive atomic number) is Argon (Ar), which is in Group 18 and has an atomic number of 18.

- **Element C**: The element that comes after Argon is Potassium (K), which is in Group 1 and has an atomic number of 19.
...