1. Which of the following alkali metals forms the most stable peroxide?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Rubidium
Answer: (c) Potassium
Explanation: Among alkali metals, potassium readily forms a stable peroxide. The stability of peroxides increases as we move down the group because the larger size of the cation stabilizes the large peroxide anion (O22−)(O22−). Potassium is larger than sodium and lithium, and hence forms a more stable peroxide.
2. Which of the following alkali metal ions is the smallest in size?
- (a) Li⁺
- (b) Na⁺
- (c) K⁺
- (d) Cs⁺
Answer: (a) Li⁺
Explanation: As we move down Group 1 (alkali metals), the size of the ions increases due to the addition of electron shells. Hence, the size order is Li⁺ < Na⁺ < K⁺ < Cs⁺. Lithium ion (Li⁺) is the smallest.
3. Which of the following alkaline earth metal carbonates is least soluble in water?
- (a) BeCO₃
- (b) MgCO₃
- (c) CaCO₃
- (d) BaCO₃
Answer: (d) BaCO₃
Explanation: The solubility of alkaline earth metal carbonates decreases as we move down the group. This is because the lattice energy decreases more slowly than the hydration energy. Therefore, BaCO₃ is the least soluble.
4. Which of the following compounds is used in the preparation of plaster of Paris?
- (a) MgSO₄
- (b) CaSO₄·2H₂O
- (c) BaSO₄
- (d) Na₂SO₄
Answer: (b) CaSO₄·2H₂O
Explanation: Plaster of Paris is chemically calcium sulfate hemihydrate (CaSO₄·½H₂O), which is prepared by heating gypsum, CaSO₄·2H₂O, to about 373 K. When water is removed partially from gypsum, it forms Plaster of Paris.
5. Which of the following is the correct order of ionization enthalpy for alkali metals?
- (a) Li > Na > K > Rb
- (b) Na > Li > K > Rb
- (c) K > Na > Li > Rb
- (d) Rb > K > Na > Li
Answer: (a) Li > Na > K > Rb
Explanation: As we move down the group in alkali metals, the ionization enthalpy decreases due to the increasing atomic size and the screening effect, which reduces the effective nuclear charge felt by the outermost electron. Hence, the correct order is Li > Na > K > Rb.
6. Which of the following alkaline earth metals does not impart color to the flame?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (a) Beryllium
Explanation: Beryllium and magnesium do not impart any color to the flame because their electrons are too tightly bound to be excited by the flame’s heat. Calcium, strontium, and other heavier alkaline earth metals do impart characteristic colors.
7. Which alkali metal is stored under kerosene oil?
- (a) Sodium
- (b) Magnesium
- (c) Calcium
- (d) Beryllium
Answer: (a) Sodium
Explanation: Sodium is highly reactive and readily reacts with moisture and oxygen in the air, so it is stored under kerosene oil to prevent it from reacting with air and water.
8. Which of the following oxides is amphoteric?
- (a) Na₂O
- (b) K₂O
- (c) BeO
- (d) MgO
Answer: (c) BeO
Explanation: Beryllium oxide (BeO) is amphoteric, meaning it can react with both acids and bases. Other oxides in the group, such as Na₂O and K₂O, are basic, while MgO is weakly basic.
9. Which of the following elements forms the most soluble hydroxide?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: The solubility of alkali metal hydroxides increases as we move down the group due to the decreasing lattice energy. Thus, cesium hydroxide (CsOH) is the most soluble.
10. Which of the following is a diagonal relationship observed in the periodic table?
- (a) Li and Be
- (b) Li and Mg
- (c) Na and Be
- (d) K and Ca
Answer: (b) Li and Mg
Explanation: The diagonal relationship refers to the similarity in properties between elements in different groups that are positioned diagonally to each other in the periodic table. Lithium (Group 1) shows similarities with magnesium (Group 2) due to comparable ionic radii and polarizing power.
11. Which of the following compounds is used as an antacid?
- (a) Mg(OH)₂
- (b) Ca(OH)₂
- (c) NaOH
- (d) KOH
Answer: (a) Mg(OH)₂
Explanation: Magnesium hydroxide, also known as “milk of magnesia,” is used as an antacid because it neutralizes stomach acid without causing excessive alkalinity.
12. Which of the following elements does not show the diagonal relationship in the periodic table?
- (a) Li
- (b) Be
- (c) Na
- (d) Mg
Answer: (c) Na
Explanation: Sodium (Na) does not show a diagonal relationship with any element. The diagonal relationship is observed between lithium (Li) and magnesium (Mg), and between beryllium (Be) and aluminum (Al).
13. Which alkali metal forms the strongest base?
- (a) LiOH
- (b) NaOH
- (c) KOH
- (d) CsOH
Answer: (d) CsOH
Explanation: Cesium hydroxide (CsOH) is the strongest base among alkali metal hydroxides because the basicity increases as we move down the group due to the increasing ionic size and decreasing lattice energy.
14. Which alkaline earth metal is used in the preparation of cement?
- (a) Magnesium
- (b) Calcium
- (c) Barium
- (d) Strontium
Answer: (b) Calcium
Explanation: Calcium is a key element in the preparation of cement, specifically in the form of calcium carbonate (CaCO₃) and calcium silicates, which are used to form the clinker that is ground to make cement.
15. Which of the following elements forms superoxides?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Rubidium
Answer: (d) Rubidium
Explanation: Heavier alkali metals like rubidium (Rb) and cesium (Cs) form superoxides (RbO₂ and CsO₂) due to their large ionic sizes, which stabilize the superoxide ion (O2−)(O2−). Potassium also forms superoxides under certain conditions.
16. Which of the following elements is the most electropositive?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium is the most electropositive element due to its large atomic size and low ionization energy, which makes it easier to lose an electron.
17. Which alkali metal forms the most stable chloride?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium chloride (NaCl) is the most stable chloride due to its optimal size ratio between Na⁺ and Cl⁻ ions, resulting in a stable ionic lattice with high lattice energy.
18. Which of the following elements shows a diagonal relationship with aluminum?
- (a) Lithium
- (b) Beryllium
- (c) Magnesium
- (d) Sodium
Answer: (b) Beryllium
Explanation: Beryllium (Be) shows a diagonal relationship with aluminum (Al). Both form covalent compounds, have amphoteric oxides, and their hydroxides dissolve in excess alkali to form beryllates and aluminates, respectively.
19. Which alkali metal carbonate is least stable thermally?
- (a) Li₂CO₃
- (b) Na₂CO₃
- (c) K₂CO₃
- (d) Cs₂CO₃
Answer: (a) Li₂CO₃
Explanation: Lithium carbonate (Li₂CO₃) is less stable than the carbonates of other alkali metals and decomposes at a lower temperature due to the small size of the lithium ion, which has a higher polarizing power, leading to the distortion of the carbonate ion.
20. Which alkaline earth metal hydroxide is most soluble in water?
- (a) Be(OH)₂
- (b) Mg(OH)₂
- (c) Ca(OH)₂
- (d) Ba(OH)₂
Answer: (d) Ba(OH)₂
Explanation: The solubility of alkaline earth metal hydroxides increases as we move down the group. Thus, barium hydroxide (Ba(OH)2)(Ba(OH)2) is the most soluble in water.
21. Which of the following alkali metal salts is used as a table salt?
- (a) KCl
- (b) NaCl
- (c) LiCl
- (d) CsCl
Answer: (b) NaCl
Explanation: Sodium chloride (NaCl), commonly known as table salt, is used in daily life for food seasoning and preservation. It is an essential part of the human diet.
22. Which of the following statements is incorrect regarding alkali metals?
- (a) Alkali metals are highly electropositive.
- (b) Alkali metals have low ionization energies.
- (c) Alkali metals form basic oxides.
- (d) Alkali metals readily form covalent compounds.
Answer: (d) Alkali metals readily form covalent compounds.
Explanation: Alkali metals form ionic compounds, not covalent compounds, due to their high electropositivity and tendency to lose an electron easily.
23. Which of the following alkaline earth metals does not form nitrates directly?
- (a) Magnesium
- (b) Calcium
- (c) Beryllium
- (d) Strontium
Answer: (c) Beryllium
Explanation: Beryllium, due to its small size and high charge density, forms compounds with covalent character and does not form nitrates directly like other alkaline earth metals. It usually reacts with nitrogen to form beryllium nitride (Be₃N₂).
24. Which alkali metal forms the least soluble carbonate?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium carbonate (Li₂CO₃) is the least soluble among alkali metal carbonates due to the small size of the lithium ion, which causes a high lattice energy.
25. Which of the following statements is true about magnesium and calcium?
- (a) Both form amphoteric oxides.
- (b) Both are used in fireworks.
- (c) Both react with water at room temperature.
- (d) Both are used in the manufacture of cement.
Answer: (b) Both are used in fireworks.
Explanation: Magnesium burns with a bright white flame and is used in fireworks, while calcium compounds impart an orange-red color to fireworks. Both are used for pyrotechnic purposes.
26. Which of the following statements is correct regarding the solubility of alkaline earth metal sulfates?
- (a) Solubility increases down the group.
- (b) Solubility decreases down the group.
- (c) Solubility remains constant down the group.
- (d) Solubility first increases and then decreases.
Answer: (b) Solubility decreases down the group.
Explanation: The solubility of alkaline earth metal sulfates (e.g., BeSO₄, MgSO₄, CaSO₄, etc.) decreases as we move down the group due to the decreasing hydration energy.
27. Which of the following compounds is used as a drying agent?
- (a) NaOH
- (b) CaCl₂
- (c) KOH
- (d) MgO
Answer: (b) CaCl₂
Explanation: Calcium chloride (CaCl₂) is hygroscopic and can absorb water vapor from the atmosphere, making it a good drying agent.
28. Which alkali metal hydroxide is used in the manufacture of soaps?
- (a) LiOH
- (b) NaOH
- (c) KOH
- (d) CsOH
Answer: (b) NaOH
Explanation: Sodium hydroxide (NaOH), also known as caustic soda, is used in the manufacture of soaps by saponifying fats and oils.
29. Which of the following elements forms an oxide that is used in the manufacture of refractory bricks?
- (a) Magnesium
- (b) Calcium
- (c) Sodium
- (d) Potassium
Answer: (a) Magnesium
Explanation: Magnesium oxide (MgO) has high thermal stability and is used in the manufacture of refractory bricks, which can withstand high temperatures.
30. Which of the following alkali metals has the highest melting point?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium has the highest melting point among alkali metals due to its small atomic size, which results in stronger metallic bonds.
31. Which of the following elements forms a soluble sulfate?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Barium
Answer: (b) Magnesium
Explanation: Magnesium sulfate (MgSO₄), also known as Epsom salt, is soluble in water, while the solubility of other alkaline earth metal sulfates decreases down the group.
32. Which of the following alkaline earth metals has the lowest first ionization energy?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Barium
Answer: (d) Barium
Explanation: The first ionization energy decreases down the group for alkaline earth metals. Barium, being the heaviest element, has the lowest first ionization energy.
33. Which of the following alkaline earth metal oxides is most basic?
- (a) BeO
- (b) MgO
- (c) CaO
- (d) BaO
Answer: (d) BaO
Explanation: Basicity increases as we move down the group in alkaline earth metal oxides. Barium oxide (BaO) is the most basic because of the larger size of the Ba²⁺ ion.
34. Which of the following compounds is a component of baking powder?
- (a) K₂CO₃
- (b) NaHCO₃
- (c) Na₂CO₃
- (d) CaCO₃
Answer: (b) NaHCO₃
Explanation: Sodium bicarbonate (NaHCO₃) is a key ingredient in baking powder. It releases carbon dioxide when heated or in the presence of acid, causing dough to rise.
35. Which of the following elements forms the most soluble nitrate?
- (a) Magnesium
- (b) Barium
- (c) Calcium
- (d) Sodium
Answer: (d) Sodium
Explanation: Sodium nitrate (NaNO₃) is highly soluble in water, whereas the solubility of nitrates of alkaline earth metals decreases down the group.
36. Which of the following alkaline earth metals is used in medicine to treat osteoporosis?
- (a) Calcium
- (b) Magnesium
- (c) Strontium
- (d) Beryllium
Answer: (c) Strontium
Explanation: Strontium ranelate is used in the treatment of osteoporosis, a condition that weakens bones, making them fragile and more likely to break.
37. Which of the following compounds is used in the purification of bauxite ore in the Bayer process?
- (a) NaOH
- (b) KOH
- (c) CaO
- (d) MgO
Answer: (a) NaOH
Explanation: Sodium hydroxide (NaOH) is used in the Bayer process to purify bauxite ore. It dissolves the alumina (Al₂O₃) to form soluble sodium aluminate, leaving behind the impurities.
38. Which of the following is the correct order of atomic radii for alkali metals?
- (a) Li > Na > K > Rb
- (b) Na > Li > K > Rb
- (c) Rb > K > Na > Li
- (d) K > Na > Li > Rb
Answer: (c) Rb > K > Na > Li
Explanation: Atomic radii increase as we move down Group 1 (alkali metals) due to the addition of electron shells. Thus, the correct order is Rb > K > Na > Li.
39. Which of the following alkaline earth metals has the highest second ionization energy?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (a) Beryllium
Explanation: Beryllium has the highest second ionization energy among the alkaline earth metals because it requires more energy to remove a second electron from the small, highly charged Be²⁺ ion.
40. Which alkali metal is used in atomic clocks?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium is used in atomic clocks because of the precise frequency of its electron transitions. Cesium atomic clocks are highly accurate for measuring time.
41. Which of the following alkali metals has the lowest density?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium has the lowest density among alkali metals. The density increases as we move down the group, except for potassium, which is less dense than sodium due to its atomic structure.
42. Which of the following alkaline earth metals has the highest melting point?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (a) Beryllium
Explanation: Beryllium has the highest melting point among the alkaline earth metals due to its small size, strong metallic bonds, and high lattice energy.
43. Which of the following compounds is used as a drying agent in the laboratory?
- (a) Na₂CO₃
- (b) CaO
- (c) NaOH
- (d) MgSO₄
Answer: (b) CaO
Explanation: Calcium oxide (CaO), also known as quicklime, is a strong drying agent that readily absorbs moisture from the surroundings.
44. Which alkali metal reacts most vigorously with water?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium reacts explosively with water because it has a large atomic size and low ionization energy, which make it highly reactive. As we move down the group, the reactivity with water increases.
45. Which alkaline earth metal is commonly found in chlorophyll?
- (a) Magnesium
- (b) Calcium
- (c) Beryllium
- (d) Strontium
Answer: (a) Magnesium
Explanation: Magnesium is a central element in chlorophyll, the pigment that plants use for photosynthesis. It is coordinated with nitrogen atoms in the chlorophyll molecule.
46. Which of the following compounds is used as a desiccant in anhydrous form?
- (a) Na₂SO₄
- (b) CaSO₄
- (c) K₂SO₄
- (d) Li₂SO₄
Answer: (b) CaSO₄
Explanation: Anhydrous calcium sulfate (CaSO₄) is commonly used as a desiccant (drying agent) due to its ability to absorb water.
47. Which of the following elements forms an oxide used in the manufacture of Portland cement?
- (a) Barium
- (b) Calcium
- (c) Magnesium
- (d) Strontium
Answer: (b) Calcium
Explanation: Calcium oxide (CaO), derived from limestone, is a key ingredient in the manufacture of Portland cement. It reacts with other compounds to form clinker, which is then ground into cement.
48. Which of the following compounds does not undergo thermal decomposition easily?
- (a) Li₂CO₃
- (b) Na₂CO₃
- (c) K₂CO₃
- (d) Cs₂CO₃
Answer: (b) Na₂CO₃
Explanation: Sodium carbonate (Na₂CO₃) does not decompose easily upon heating. Lithium carbonate decomposes at a relatively lower temperature due to the smaller size of the lithium ion, which polarizes the carbonate ion.
49. Which of the following compounds is commonly known as washing soda?
- (a) Na₂CO₃
- (b) NaHCO₃
- (c) NaCl
- (d) NaOH
Answer: (a) Na₂CO₃
Explanation: Sodium carbonate (Na₂CO₃), commonly known as washing soda, is used in laundry detergents to soften water and enhance cleaning.
50. Which of the following alkaline earth metal chlorides is least soluble in water?
- (a) BeCl₂
- (b) MgCl₂
- (c) CaCl₂
- (d) BaCl₂
Answer: (a) BeCl₂
Explanation: Beryllium chloride (BeCl₂) has some covalent character due to the small size of the Be²⁺ ion, making it less soluble in water compared to the other chlorides, which are more ionic.
51. Which alkali metal carbonate is used to remove permanent hardness of water?
- (a) Na₂CO₃
- (b) Li₂CO₃
- (c) K₂CO₃
- (d) Cs₂CO₃
Answer: (a) Na₂CO₃
Explanation: Sodium carbonate (Na₂CO₃), also known as washing soda, is used to remove permanent hardness of water by precipitating calcium and magnesium ions as their carbonates.
52. Which alkaline earth metal sulfate is least soluble in water?
- (a) BeSO₄
- (b) MgSO₄
- (c) CaSO₄
- (d) BaSO₄
Answer: (d) BaSO₄
Explanation: Barium sulfate (BaSO₄) is insoluble in water and is often used as a radiocontrast agent in medical imaging.
53. Which of the following compounds is used in the preparation of lime water?
- (a) CaCO₃
- (b) CaO
- (c) Ca(OH)₂
- (d) CaCl₂
Answer: (c) Ca(OH)₂
Explanation: Lime water is a dilute solution of calcium hydroxide (Ca(OH)₂) in water. It is used to test for carbon dioxide, as it turns milky when CO₂ is passed through it due to the formation of calcium carbonate.
54. Which of the following alkali metal ions has the highest hydration energy?
- (a) Li⁺
- (b) Na⁺
- (c) K⁺
- (d) Cs⁺
Answer: (a) Li⁺
Explanation: Lithium ion (Li⁺) has the highest hydration energy among alkali metals due to its small size and high charge density, making it strongly attracted to water molecules.
55. Which of the following elements is used in thermonuclear reactions?
- (a) Lithium
- (b) Sodium
- (c) Calcium
- (d) Magnesium
Answer: (a) Lithium
Explanation: Lithium is used in thermonuclear reactions as a source of tritium and as a material for fusion reactions.
56. Which of the following is a characteristic property of alkali metals?
- (a) They form acidic oxides.
- (b) They are good conductors of electricity.
- (c) They have high ionization energies.
- (d) They do not react with water.
Answer: (b) They are good conductors of electricity.
Explanation: Alkali metals are excellent conductors of electricity due to the presence of a single valence electron, which is easily delocalized.
57. Which alkaline earth metal carbonate decomposes on heating to give lime and carbon dioxide?
- (a) MgCO₃
- (b) CaCO₃
- (c) BaCO₃
- (d) SrCO₃
Answer: (b) CaCO₃
Explanation: Calcium carbonate (CaCO₃) decomposes on heating to form calcium oxide (lime, CaO) and carbon dioxide (CO2)(CO2).
58. Which of the following elements forms an oxide that is amphoteric?
- (a) Na
- (b) K
- (c) Be
- (d) Mg
Answer: (c) Be
Explanation: Beryllium oxide (BeO) is amphoteric, meaning it can react with both acids and bases, unlike other alkaline earth metal oxides, which are basic.
59. Which of the following compounds is commonly known as slaked lime?
- (a) CaO
- (b) Ca(OH)₂
- (c) CaCO₃
- (d) CaSO₄
Answer: (b) Ca(OH)₂
Explanation: Slaked lime is the common name for calcium hydroxide (Ca(OH)2)(Ca(OH)2), which is used in the preparation of lime water and in neutralizing acidic soils.
60. Which of the following elements has the smallest ionic radius in its group?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium has the smallest ionic radius among the alkali metals due to its small atomic size and fewer electron shells.
61. Which of the following is the most basic oxide?
- (a) Li₂O
- (b) Na₂O
- (c) K₂O
- (d) Cs₂O
Answer: (d) Cs₂O
Explanation: As we move down the alkali metal group, the basicity of oxides increases. Cesium oxide (Cs₂O) is the most basic among alkali metal oxides due to the large size and lower electronegativity of the cesium ion.
62. Which of the following alkaline earth metals forms a water-insoluble hydroxide?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Barium
Answer: (d) Barium
Explanation: Barium hydroxide (Ba(OH)2)(Ba(OH)2) is slightly soluble in water, but it is much less soluble than the hydroxides of calcium and magnesium. Solubility of hydroxides increases down the group, but barium hydroxide is sparingly soluble compared to the lighter alkaline earth hydroxides.
63. Which of the following metals forms a peroxide when heated in oxygen?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium forms sodium peroxide (Na₂O₂) when heated in excess oxygen, while other alkali metals like potassium and cesium form superoxides (MO2)(MO2) under similar conditions.
64. Which of the following alkaline earth metal sulfates is the most soluble in water?
- (a) BeSO₄
- (b) MgSO₄
- (c) CaSO₄
- (d) BaSO₄
Answer: (a) BeSO₄
Explanation: Beryllium sulfate (BeSO₄) is the most soluble in water among the alkaline earth metal sulfates. The solubility of sulfates decreases as we move down the group.
65. Which of the following alkali metals has the highest tendency to form a superoxide?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium, due to its large size and low ionization energy, has the highest tendency to form superoxides (CsO₂) compared to other alkali metals.
66. Which of the following elements forms an oxide that is used in the treatment of cancer?
- (a) Barium
- (b) Calcium
- (c) Magnesium
- (d) Radium
Answer: (d) Radium
Explanation: Radium, due to its radioactivity, is used in the treatment of certain types of cancer. Radium oxide is one of its compounds used for radiotherapy.
67. Which alkali metal ion is commonly used in salt substitutes for people on low-sodium diets?
- (a) Li⁺
- (b) Na⁺
- (c) K⁺
- (d) Cs⁺
Answer: (c) K⁺
Explanation: Potassium chloride (KCl) is commonly used as a salt substitute for individuals on low-sodium diets because potassium is essential for the body and does not raise blood pressure like sodium.
68. Which of the following alkaline earth metals is the least reactive towards water?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (a) Beryllium
Explanation: Beryllium does not react with water under normal conditions due to the formation of a passivating oxide layer, making it the least reactive alkaline earth metal towards water.
69. Which of the following alkali metal compounds is used as an antacid?
- (a) NaHCO₃
- (b) Na₂CO₃
- (c) K₂CO₃
- (d) Li₂CO₃
Answer: (a) NaHCO₃
Explanation: Sodium bicarbonate (NaHCO₃), commonly known as baking soda, is used as an antacid to neutralize stomach acid and relieve indigestion and heartburn.
70. Which alkaline earth metal forms a nitrate that decomposes to give nitrite and oxygen?
- (a) Calcium
- (b) Magnesium
- (c) Barium
- (d) Strontium
Answer: (c) Barium
Explanation: Barium nitrate (Ba(NO₃)₂) decomposes upon heating to form barium nitrite (Ba(NO₂)₂) and oxygen. This is a common decomposition pattern for nitrates of heavier alkaline earth metals.
71. Which of the following alkali metals forms the least stable oxide?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium oxide (Cs₂O) is the least stable among alkali metal oxides due to the large size of the cesium ion and its relatively low lattice energy.
72. Which alkaline earth metal sulfate is used in medical imaging?
- (a) Beryllium sulfate
- (b) Magnesium sulfate
- (c) Calcium sulfate
- (d) Barium sulfate
Answer: (d) Barium sulfate
Explanation: Barium sulfate (BaSO₄) is insoluble and is used as a radiocontrast agent in X-ray imaging of the gastrointestinal tract because it absorbs X-rays well and is not absorbed by the body.
73. Which of the following alkali metals forms a highly soluble bicarbonate in water?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium bicarbonate (NaHCO₃) is highly soluble in water and is commonly used in baking, fire extinguishers, and as an antacid.
74. Which of the following alkaline earth metals forms a stable hydride?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Barium
Answer: (b) Magnesium
Explanation: Magnesium hydride (MgH₂) is a stable compound used in hydrogen storage. It decomposes at high temperatures to release hydrogen gas.
75. Which of the following alkali metal halides is least soluble in water?
- (a) LiF
- (b) NaF
- (c) KF
- (d) CsF
Answer: (a) LiF
Explanation: Lithium fluoride (LiF) is the least soluble in water among the alkali metal halides due to the high lattice energy resulting from the small size of the lithium ion.
76. Which of the following alkaline earth metal oxides is amphoteric?
- (a) BeO
- (b) MgO
- (c) CaO
- (d) BaO
Answer: (a) BeO
Explanation: Beryllium oxide (BeO) is amphoteric, meaning it can react with both acids and bases. The other alkaline earth metal oxides are basic in nature.
77. Which of the following alkali metals is liquid at room temperature?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) None of these
Answer: (d) None of these
Explanation: None of the alkali metals are liquid at room temperature. All alkali metals are solid at room temperature, although they have relatively low melting points.
78. Which of the following compounds is used to de-ice roads in winter?
- (a) NaCl
- (b) KCl
- (c) CaCl₂
- (d) MgCl₂
Answer: (c) CaCl₂
Explanation: Calcium chloride (CaCl₂) is used to de-ice roads in winter because it lowers the freezing point of water and generates heat as it dissolves, making it effective in melting ice.
79. Which of the following elements forms the hardest oxide?
- (a) Lithium
- (b) Beryllium
- (c) Magnesium
- (d) Calcium
Answer: (b) Beryllium
Explanation: Beryllium oxide (BeO) is extremely hard and has a high melting point. It is used in specialized applications like ceramics and nuclear reactors due to its hardness and stability.
80. Which alkali metal hydroxide is the strongest base?
- (a) LiOH
- (b) NaOH
- (c) KOH
- (d) CsOH
Answer: (d) CsOH
Explanation: Cesium hydroxide (CsOH) is the strongest base among the alkali metal hydroxides due to the large size of the cesium ion, which makes it highly dissociable in water.
81. Which of the following compounds is known as bleaching powder?
- (a) CaO
- (b) CaCO₃
- (c) Ca(OH)₂
- (d) Ca(OCl)₂
Answer: (d) Ca(OCl)₂
Explanation: Bleaching powder is calcium hypochlorite (Ca(OCl)2)(Ca(OCl)2), which is used as a disinfectant and bleaching agent.
82. Which alkali metal is the least reactive?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium is the least reactive alkali metal due to its small size and relatively high ionization energy, making it less reactive compared to the other alkali metals.
83. Which of the following alkaline earth metal salts is commonly used in fireworks?
- (a) Magnesium chloride
- (b) Calcium sulfate
- (c) Strontium nitrate
- (d) Barium sulfate
Answer: (c) Strontium nitrate
Explanation: Strontium salts, particularly strontium nitrate (Sr(NO3)2)(Sr(NO3)2), are used in fireworks to produce a bright red flame.
84. Which alkali metal is used as a coolant in nuclear reactors?
- (a) Sodium
- (b) Potassium
- (c) Lithium
- (d) Rubidium
Answer: (a) Sodium
Explanation: Liquid sodium is used as a coolant in nuclear reactors due to its excellent thermal conductivity and high heat capacity.
85. Which of the following alkaline earth metals is used in lightweight alloys?
- (a) Calcium
- (b) Beryllium
- (c) Strontium
- (d) Barium
Answer: (b) Beryllium
Explanation: Beryllium is used in lightweight alloys for aerospace applications because of its low density, high strength, and corrosion resistance.
86. Which alkali metal forms the most stable carbonate?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium carbonate (Na2CO3)(Na2CO3) is more stable than lithium carbonate, which decomposes upon heating, and potassium and cesium carbonates are highly soluble and reactive.
87. Which of the following alkaline earth metals forms an insoluble sulfate?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Barium
Answer: (d) Barium
Explanation: Barium sulfate (BaSO₄) is insoluble in water and is used in medical imaging because of its low toxicity and opacity to X-rays.
88. Which of the following alkali metals has the highest melting point?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium has the highest melting point among the alkali metals due to its small atomic size and strong metallic bonds.
89. Which alkaline earth metal hydroxide is the least soluble in water?
- (a) Be(OH)₂
- (b) Mg(OH)₂
- (c) Ca(OH)₂
- (d) Ba(OH)₂
Answer: (a) Be(OH)₂
Explanation: Beryllium hydroxide (Be(OH)2)(Be(OH)2) is amphoteric and the least soluble in water compared to the other alkaline earth metal hydroxides.
90. Which of the following alkali metals does not form a superoxide?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium does not form a superoxide because its small size and high ionization energy favor the formation of simple oxides (Li2O)(Li2O).
91. Which alkaline earth metal is used in the manufacture of cement?
- (a) Calcium
- (b) Magnesium
- (c) Strontium
- (d) Barium
Answer: (a) Calcium
Explanation: Calcium is a major component of limestone and is used in the manufacture of cement. Calcium oxide (CaO)(CaO), also known as lime, is a key ingredient in cement production.
92. Which alkali metal ion is most effective in conducting electricity in aqueous solution?
- (a) Li⁺
- (b) Na⁺
- (c) K⁺
- (d) Cs⁺
Answer: (b) Na⁺
Explanation: Sodium ion (Na+)(Na+) is small and has high mobility in aqueous solution, making it highly effective in conducting electricity.
93. Which alkaline earth metal forms a hydride used as a reducing agent in organic chemistry?
- (a) Calcium
- (b) Magnesium
- (c) Barium
- (d) Lithium
Answer: (b) Magnesium
Explanation: Magnesium hydride (MgH2)(MgH2) is used as a reducing agent in organic chemistry due to its ability to release hydrogen gas during chemical reactions.
94. Which alkali metal is most commonly used in batteries?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium is commonly used in batteries due to its high energy density, low weight, and ability to release energy efficiently.
95. Which of the following alkaline earth metal oxides is used in the manufacture of refractory bricks?
- (a) Magnesium oxide
- (b) Calcium oxide
- (c) Barium oxide
- (d) Strontium oxide
Answer: (a) Magnesium oxide
Explanation: Magnesium oxide (MgO)(MgO), also known as magnesia, is used in the manufacture of refractory bricks due to its high melting point and resistance to heat and corrosion.
96. Which of the following alkali metals has the lowest boiling point?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium has the lowest boiling point among the alkali metals due to its large atomic size and weaker metallic bonds.
97. Which of the following alkaline earth metals forms a nitrate that does not decompose on heating?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (b) Magnesium
Explanation: Magnesium nitrate decomposes to form magnesium oxide, nitrogen dioxide, and oxygen upon heating. The decomposition temperature varies for different nitrates, but magnesium nitrate decomposes at a relatively higher temperature than others.
98. Which alkali metal is most abundant in the Earth’s crust?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Rubidium
Answer: (b) Sodium
Explanation: Sodium is the most abundant alkali metal in the Earth’s crust, primarily found in the form of sodium chloride (NaCl) and other minerals.
99. Which alkaline earth metal forms the hardest hydride?
- (a) Calcium
- (b) Magnesium
- (c) Beryllium
- (d) Strontium
Answer: (c) Beryllium
Explanation: Beryllium hydride (BeH2)(BeH2) is hard and has a complex polymeric structure, making it much harder than the hydrides of other alkaline earth metals.
100. Which alkali metal forms a hydroxide used in soap making?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium hydroxide (NaOH), also known as caustic soda, is widely used in the manufacture of soap. It saponifies fats to produce soap and glycerol.
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