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1. The s-block elements of the periodic table comprise Groups:
A. 1 and 2
B. 13 and 14
C. 17 and 18
D. 3 to 12
Answer: A. 1 and 2
Explanation: The s-block consists of Groups 1 (alkali metals) and 2 (alkaline earth metals), where the valence electrons occupy an s-orbital.
2. Group 1 elements (excluding hydrogen) are commonly known as the:
A. Alkali metals
B. Alkaline earth metals
C. Halogens
D. Noble gases
Answer: A. Alkali metals
Explanation: The elements of Group 1, apart from hydrogen, are collectively referred to as alkali metals due to their strongly basic hydroxides.
3. Group 2 elements are commonly known as the:
A. Alkaline earth metals
B. Alkali metals
C. Halogens
D. Transition metals
Answer: A. Alkaline earth metals
Explanation: Group 2 elements are called alkaline earth metals, as their oxides and hydroxides are basic (alkaline) and they occur commonly in the earth's crust.
4. Alkali metals have a general valence electron configuration of:
A. ns¹
B. ns²
C. ns²np¹
D. ns²np⁵
Answer: A. ns¹
Explanation: Alkali metals possess a single electron in their outermost s-orbital, giving them the general configuration ns¹.
5. Alkaline earth metals have a general valence electron configuration of:
A. ns²
B. ns¹
C. ns²np¹
D. ns²np⁵
Answer: A. ns²
Explanation: Alkaline earth metals have two electrons in their outermost s-orbital, giving them the general configuration ns².
6. Alkali metals are generally characterised by:
A. Low ionisation energy and high reactivity
B. High ionisation energy and low reactivity
C. No reactivity at all
D. Only negative oxidation states
Answer: A. Low ionisation energy and high reactivity
Explanation: Due to having just one loosely held valence electron, alkali metals exhibit low ionisation energies and are highly reactive.
7. The common oxidation state exhibited by alkali metals in their compounds is:
A. +1
B. +2
C. -1
D. 0 only
Answer: A. +1
Explanation: Alkali metals characteristically lose their single valence electron, resulting in a stable +1 oxidation state in most compounds.
8. The common oxidation state exhibited by alkaline earth metals in their compounds is:
A. +2
B. +1
C. -2
D. 0 only
Answer: A. +2
Explanation: Alkaline earth metals typically lose both valence electrons, resulting in a stable +2 oxidation state in their compounds.
9. Which alkali metal is the lightest and has the smallest atomic radius among the group?
A. Lithium
B. Sodium
C. Potassium
D. Caesium
Answer: A. Lithium
Explanation: Lithium, being at the top of Group 1, has the smallest atomic radius and lowest atomic mass among the alkali metals.
10. Which alkali metal is the heaviest naturally occurring member of the group, known for its high reactivity?
A. Caesium
B. Lithium
C. Sodium
D. Potassium
Answer: A. Caesium
Explanation: Caesium, positioned at the bottom of the naturally occurring alkali metals, exhibits extremely high reactivity due to its large atomic size and low ionisation energy.
11. Alkali metals react with water to produce hydrogen gas and:
A. Metal hydroxides
B. Metal oxides only
C. Metal hydrides only
D. Metal carbonates only
Answer: A. Metal hydroxides
Explanation: When alkali metals react with water, they produce hydrogen gas along with the corresponding metal hydroxide, often accompanied by significant heat release.
12. Alkaline earth metals generally react with water:
A. Less vigorously than alkali metals
B. More vigorously than alkali metals
C. Not at all under any conditions
D. Only when frozen
Answer: A. Less vigorously than alkali metals
Explanation: Due to higher ionisation energies compared to alkali metals, alkaline earth metals typically react with water less vigorously.
13. The compound formed when alkali metals burn in excess oxygen (for metals like sodium) is generally a:
A. Peroxide
B. Simple oxide only
C. Hydride only
D. Carbonate only
Answer: A. Peroxide
Explanation: Sodium, when burnt in excess oxygen, characteristically forms sodium peroxide (Na₂O₂) rather than the simple oxide.
14. Lithium differs from other alkali metals in several properties primarily due to its:
A. Small size and high polarising power
B. Large size only
C. Lack of any valence electron
D. Position in Group 2
Answer: A. Small size and high polarising power
Explanation: Lithium's unusually small ionic size gives it a high charge density and polarising power, leading to distinct chemical behaviour compared to other alkali metals.
15. Beryllium shows anomalous behaviour compared to other alkaline earth metals mainly due to its:
A. Very small atomic and ionic size
B. Very large atomic size
C. Lack of valence electrons
D. High atomic number
Answer: A. Very small atomic and ionic size
Explanation: Beryllium's exceptionally small size compared to other Group 2 elements results in distinctly different chemical properties, similar to a 'diagonal relationship' effect.
16. The diagonal relationship observed in the periodic table describes similarities between:
A. An element and the one diagonally placed in the next group and period
B. Elements in the same group only
C. Elements in the same period only
D. Only noble gases
Answer: A. An element and the one diagonally placed in the next group and period
Explanation: The diagonal relationship refers to similarities in properties between certain elements positioned diagonally adjacent to each other, such as lithium and magnesium.
17. Sodium carbonate is commonly known as:
A. Washing soda
B. Baking soda
C. Caustic soda
D. Bleaching powder
Answer: A. Washing soda
Explanation: Sodium carbonate (Na₂CO₃) is widely known by its common name, washing soda, and is used extensively in cleaning and industrial processes.
18. Sodium bicarbonate is commonly known as:
A. Baking soda
B. Washing soda
C. Caustic soda
D. Bleaching powder
Answer: A. Baking soda
Explanation: Sodium bicarbonate (NaHCO₃) is popularly referred to as baking soda, widely used in cooking and as a mild antacid.
19. Sodium hydroxide is commonly known as:
A. Caustic soda
B. Washing soda
C. Baking soda
D. Bleaching powder
Answer: A. Caustic soda
Explanation: Sodium hydroxide (NaOH) is commonly called caustic soda, widely used in soap manufacturing and various industrial applications.
20. Calcium oxide, formed by heating limestone, is commonly known as:
A. Quicklime
B. Slaked lime
C. Gypsum
D. Plaster of Paris
Answer: A. Quicklime
Explanation: Calcium oxide (CaO), produced by strongly heating limestone (calcium carbonate), is commonly known as quicklime.
21. Calcium hydroxide, formed by adding water to quicklime, is commonly known as:
A. Slaked lime
B. Quicklime
C. Gypsum
D. Limestone
Answer: A. Slaked lime
Explanation: Calcium hydroxide (Ca(OH)₂), formed when quicklime reacts with water, is commonly referred to as slaked lime.
22. Plaster of Paris is chemically known as:
A. Calcium sulphate hemihydrate
B. Calcium carbonate
C. Calcium oxide
D. Calcium hydroxide
Answer: A. Calcium sulphate hemihydrate
Explanation: Plaster of Paris is the common name for calcium sulphate hemihydrate, widely used in construction and medical casts.
23. The general trend of increasing atomic size down Group 1 and Group 2 is primarily due to the addition of new:
A. Electron shells
B. Protons in the nucleus only
C. Neutrons only
D. Isotopes
Answer: A. Electron shells
Explanation: As one moves down these groups, each successive element gains an additional electron shell, resulting in a larger atomic radius.
24. Which alkaline earth metal shows the greatest similarity to alkali metals due to its diagonal relationship with lithium?
A. Magnesium
B. Calcium
C. Strontium
D. Barium
Answer: A. Magnesium
Explanation: Magnesium exhibits notable similarities to lithium because of the diagonal relationship, showing properties intermediate between typical Group 1 and Group 2 behaviour.
25. Alkali and alkaline earth metals are typically stored under:
A. Kerosene or inert conditions to prevent reaction with air/moisture
B. Open air with no precautions
C. Water directly
D. Concentrated acid
Answer: A. Kerosene or inert conditions to prevent reaction with air/moisture
Explanation: Due to their high reactivity with atmospheric moisture and oxygen, these metals are typically stored under kerosene oil or in inert environments.
26. The flame test is used to identify alkali and alkaline earth metals based on the characteristic:
A. Colour they impart to a flame
B. Smell they produce
C. Sound they make
D. Texture of the resulting ash
Answer: A. Colour they impart to a flame
Explanation: Alkali and alkaline earth metal ions impart distinctive colours to a flame, providing a simple qualitative test for their identification.
27. Sodium imparts which characteristic colour to a flame during the flame test?
A. Golden yellow
B. Brick red
C. Lilac
D. Crimson red
Answer: A. Golden yellow
Explanation: Sodium compounds characteristically produce a distinctive golden-yellow colour when introduced into a flame.
28. Potassium imparts which characteristic colour to a flame during the flame test?
A. Lilac (violet)
B. Golden yellow
C. Brick red
D. Apple green
Answer: A. Lilac (violet)
Explanation: Potassium compounds characteristically produce a lilac or pale violet colour when tested in a flame.
29. Calcium imparts which characteristic colour to a flame during the flame test?
A. Brick red
B. Golden yellow
C. Lilac
D. Apple green
Answer: A. Brick red
Explanation: Calcium compounds characteristically produce a brick-red colour when subjected to the flame test.
30. The general reactivity of alkali metals with water, oxygen and halogens tends to _____ down the group.
A. Increase
B. Decrease
C. Remain constant
D. Become zero
Answer: A. Increase
Explanation: As atomic size increases and ionisation energy decreases down the group, the overall reactivity of alkali metals tends to increase.
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