Ncert Exercises & Solutions

Which of the following represents the correct order of non-metallic character among boron (B), carbon (C), nitrogen (N), fluorine (F) and silicon (Si)?

1. B > C > Si > N > F

2. Si > C > B > N > F

3. F > N > C > B > Si

4. F > N > C > Si > B

Hint: Non-metallic character generally increases from left to right across a period

Step 1: Periodic trends

Across a period, effective nuclear charge generally increases, resulting in a greater tendency to attract electrons.
Down a group, atomic size and shielding increase, generally reducing non-metallic character.

Step 2: Compare the given elements

Fluorine (F): Has the highest non-metallic character among the given elements.
Nitrogen (N): Is less non-metallic than fluorine but more non-metallic than carbon.
Carbon (C): Has greater non-metallic character than boron.
Boron (B): Is more non-metallic than silicon according to the usual periodic trend.
Silicon (Si): Has the lowest non-metallic character among these elements.

Step 3: Arrange in decreasing order

F > N > C > B > Si

Therefore, Option 3 represents the correct decreasing order of non-metallic character.

Final Answer: Option 3 — F > N > C > B > Si