Practise 37 real Federal Board questions on s and p Block elements from 2023 to 2026. See the answer and explanation as soon as you answer.
s and p Block elements is one of the 19 main chapters in our Federal Board FSC Chemistry question bank (12th class), and about 7% of its real questions come from it. Tayyari Karo has 37 real questions on this chapter from 2023 to 2026; 11 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 25 medium, 8 hard, 4 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Which compound is least soluble in water?
Answer: D. BaSO₄
Solubility of Group-II sulfates decreases down the group due to decreasing hydration energy relative to lattice energy; BaSO₄ is the least soluble.
Which of the following has lowest density?
Answer: B. Li
Lithium has an unusually low density (0.53 g/cm³), the lowest among all the alkali metals.
Which Group I element shows crimson red color on flame test?
Answer: D. Li
Lithium gives a characteristic crimson-red flame test color.
The allotrope of carbon known as 'Bucky ball' has how many carbon atoms in its simplest molecule?
Answer: D. 60
Buckminsterfullerene, the simplest 'bucky ball', is C₆₀.
Which halogen reduces H₂SO₄ to SO₂?
Answer: D. Br₂
HBr is a strong enough reducing agent to reduce hot concentrated H₂SO₄ to SO₂ (HI reduces it further to H₂S; HCl and HF do not reduce H₂SO₄ at all).
The formula of super oxide is:
Answer: C. O₂¹⁻
A superoxide ion contains one unpaired electron and carries a single negative charge: O₂⁻ (O₂¹⁻).
Compare the ionization energies of Group 1 and Group 2 elements. Explain the reason for the difference.
Group 2 (alkaline earth) elements have higher first ionization energies than the corresponding Group 1 (alkali) elements in the same period. This is because Group 2 elements have a higher nuclear charge (one more proton) while their valence electrons are in a similar-sized shell, so the outer electron is held more tightly (higher effective nuclear charge on it), requiring more energy to remove — despite Group 2 having a filled ns² configuration which offers some extra stability too.
Why BeCl₂ covalent while other Group 2 chlorides are ionic?
Beryllium has a very small atomic/ionic size and very high charge density (polarizing power), so by Fajan's rule it strongly polarizes the electron cloud of the large Cl⁻ ion, pulling electron density into the region between the nuclei and giving the Be-Cl bond substantial covalent character. The larger Group 2 metal ions (Mg²⁺, Ca²⁺, etc.) have much lower charge density and polarize Cl⁻ far less, so their chlorides remain predominantly ionic.
| Session | Questions |
|---|---|
| 2026 Annual | 4 |
| 2025 1st Annual | 9 |
| 2025 2nd Annual | 10 |
| 2024 Annual | 7 |
| 2023 Annual | 7 |
37 real Federal Board (FBISE) Chemistry questions on s and p Block elements from 2023 to 2026, for 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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