s-Block & p-Block Elements — 50 MCQs

1. Electronic configuration of an s-block element with atomic number 20 (Ca) is:

1. [Ar] 4s2 ✅ ([Ar]4s²)
2. [Ne] 3s1
3. [Ar] 3d10 4s1
4. [Kr] 5s2

2. Which of the following shows diagonal relationship with magnesium (Mg)?

1. Aluminum (Al)
2. Beryllium (Be) ✅
3. Calcium (Ca)
4. Sodium (Na)

3. Which s-block element forms a stable covalent oxide instead of ionic? (anomalous behaviour)

1. Potassium
2. Beryllium (forms BeO with covalent character) ✅
3. Sodium
4. Calcium

4. Which p-block group contains elements that are typically inert gases?

1. Group 16
2. Group 17
3. Group 18 (noble gases) ✅
4. Group 13

5. The element with highest first ionization enthalpy among these is:

1. Na
2. He ✅
3. Li
4. K

6. Which of the following is amphoteric?

1. Na2O
2. Al2O3 ✅
3. CaO
4. MgO

7. Which p-block element commonly shows +3 oxidation state in its compounds?

1. Oxygen
2. Aluminum (Al) ✅
3. Fluorine
4. Neon

8. Which is true about alkali metals (group 1)?

1. They are hard metals
2. They have one valence electron and are highly reactive ✅
3. They form acidic oxides
4. They are poor reducing agents

9. The inert pair effect becomes more prominent in which p-block elements?

1. Light p-block elements
2. Heavier p-block elements (e.g., Tl, Pb, Bi) ✅
3. Group 1 only
4. Noble gases only

10. Which oxide of p-block elements is acidic?

1. Na2O
2. SO3 ✅
3. CaO
4. MgO

11. Which method is commonly used to extract sodium metal industrially?

1. Electrolysis of molten NaCl (Downs process) ✅
2. Reduction of Na2O with carbon
3. Reduction of NaCl with Mg
4. Thermal decomposition

12. Which p-block element forms strong pi-bonding leading to multiple bonding with carbon?

1. Si (silicon) — forms weaker pi bonds
2. Nitrogen (forms N≡C, multiple bonds) ✅
3. Lead
4. Sodium

13. Which of the following halogens is the strongest oxidizing agent?

1. Iodine
2. Bromine
3. Fluorine ✅
4. Chlorine

14. The hydride with formula LiH is classified as:

1. Covalent hydride
2. Ionic hydride ✅
3. Metallic hydride
4. Interstitial hydride

15. Which of the following is a p-block semimetal (metalloid)?

1. Aluminum (metal)
2. Silicon ✅
3. Sodium (s-block)
4. Argon (noble gas)

16. Which s-block metal reacts vigorously with water to give hydrogen gas?

1. Magnesium
2. Potassium (K) ✅
3. Calcium only
4. Beryllium

17. The oxide B2O3 is an example of:

1. Basic oxide
2. Acidic oxide (of boron) ✅
3. Neutral oxide
4. Amphoteric oxide

18. Which element exhibits maximum covalency and ability to form pπ–pπ bonds in periodic table?

1. Bismuth
2. Carbon ✅
3. Lead
4. Radon

19. Which of the following p-block oxides is amphoteric?

1. CO2
2. Al2O3 ✅
3. SO3
4. Cl2O7

20. Which s-block element forms a protective oxide layer that prevents further corrosion?

1. Sodium
2. Magnesium (forms MgO layer) ✅
3. Potassium
4. Calcium

21. Which p-block element forms allotropes including diamond and graphite?

1. Silicon
2. Carbon ✅
3. Phosphorus only
4. Oxygen

22. Which of the following is formed when halogens react with metals?

1. Hydrides
2. Ionic halides (e.g., NaCl) ✅
3. Peroxides
4. Hydroxides only

23. Which p-block element is a good reducing agent in its lower oxidation states (e.g., +2 in Sn2+)?

1. Boron
2. Tin (Sn) ✅
3. Fluorine
4. Argon

24. Which oxide is basic among p-block elements?

1. SO2
2. Na2O (but Na is s-block) — trick: basic oxide example ✅
3. CO2
4. SO3

25. Which is correct about noble gases?

1. They readily form covalent bonds
2. They are generally inert due to full valence shells ✅
3. They are highly reactive like halogens
4. They are metals

26. Which p-block element forms acidic hydrides like H2S that are toxic gases?

1. Aluminum
2. Sulfur (H2S) ✅
3. Calcium
4. Sodium

27. Which group contains elements that commonly show -3 oxidation state (in contrast to s-block)?

1. Group 14
2. Group 15 (e.g., N in NH3 has -3) ✅
3. Group 1
4. Group 18

28. Which of following elements exhibits autocatalytic behaviour in reactions?

1. Neon
2. Iodine in certain redox reactions ✅
3. Sodium metal
4. Argon

29. The most reactive metal among alkaline earth metals is:

1. Be
2. Ba ✅
3. Mg
4. Ca

30. Which oxide is neutral (neither acidic nor basic)?

1. CO2
2. NO (nitric oxide often behaves neutral) ✅
3. SO3
4. Na2O

31. Which of these forms Lewis acidic compounds in p-block?

1. CO2
2. BF3 (electron-deficient, Lewis acid) ✅
3. NH3
4. H2O

32. Which element forms the strongest metallic bonds among the alkali metals?

1. Fr
2. Li (smallest radius → stronger metallic bonding among alkali) ✅
3. K
4. Cs

33. Which p-block element readily forms catenated chains similar to carbon?

1. Silicon (less than carbon)
2. Carbon (extensive catenation) ✅
3. Helium
4. Neon

34. Which compound demonstrates amphoteric behaviour among p-block hydroxides?

1. NaOH
2. Al(OH)3 ✅
3. HCl
4. H2SO4

35. Which of the following halides is covalent and polymeric in nature?

1. NaCl
2. AlCl3 (in solid state has covalent character and dimerizes) ✅
3. MgCl2
4. CaCl2

36. Which p-block element is used as semiconducting material in electronics?

1. Lead
2. Silicon ✅
3. Argon
4. Radon

37. The common oxidation state of oxygen in most compounds is:

1. +2
2. -2 ✅
3. 0
4. +1

38. Which s-block element does not react with water under normal conditions?

1. Na
2. Be (beryllium is resistant to reaction with water) ✅
3. K
4. Ca

39. Which oxide among p-block elements is a strong oxidizing agent?

1. CO
2. H2SO4 (conc.) can act as oxidizing agent ✅
3. SiO2
4. Al2O3

40. Which element forms the strongest acidic oxide among given?

1. Na
2. Cl (as Cl2O7/Cl2O5 strong oxides) ✅
3. Ca
4. Mg

41. Which s-block element is used in photoelectric cells because of its low work function?

1. Mg
2. Cesium (Cs) ✅
3. Be
4. Ca

42. Which p-block element is essential for nucleic acids in biology?

1. Silicon
2. Phosphorus (P) ✅
3. Argon
4. Helium

43. Which of the following is an alkaline earth metal?

1. Sodium
2. Magnesium ✅
3. Potassium
4. Aluminum

44. Boron trifluoride (BF3) is electron-deficient and acts as:

1. Lewis base
2. Lewis acid ✅
3. Strong reducing agent
4. Oxidizing agent

45. Which oxide of nitrogen is neutral and does not show acidic or basic character?

1. NO2
2. N2O (nitrous oxide often behaves neutral) ✅
3. HNO3
4. NO3

46. Which p-block element forms glass when combined with oxygen?

1. Carbon
2. Silicon (as SiO2 glass) ✅
3. Phosphorus only
4. Sodium only

47. Which s-block metal carbonate decomposes on heating to give oxide and CO2?

1. Li2CO3
2. CaCO3 ✅
3. Na2CO3 (stable)
4. K2CO3 (stable)

48. Which p-block element is used as a catalyst in Haber process (as promoter/agent)?

1. Carbon
2. Iron (Fe) but promoter includes K and Al oxides — p-block promoters sometimes used ✅
3. Neon
4. Argon

49. Which element shows allotropy among p-block elements?

1. Sodium
2. Phosphorus (white, red, black allotropes) ✅
3. Neon
4. Calcium