IMDCAT 2025 - Chemistry MCQs (Alkali Metals)

Instructions: Choose the best option for each question.

1. Which of the following is the general electronic configuration for alkali metals?
A) [Noble Gas] ns^2
B) [Noble Gas] np^1
C) [Noble Gas] ns^1
D) [Noble Gas] (n-1)d^{10} ns^1
Correct Answer: C
Explanation: Alkali metals are Group 1 elements, characterized by having one valence
electron in their outermost s-orbital.
2. As you move down Group 1 (alkali metals), the atomic radius:
A) Decreases
B) Increases
C) Remains constant
D) First decreases then increases
Correct Answer: B
Explanation: Atomic radius increases down a group because a new electron shell is added
with each successive element, increasing the distance of valence electrons from the
nucleus.
3. Which alkali metal has the highest first ionization energy?
A) Sodium
B) Potassium
C) Lithium
D) Cesium
Correct Answer: C
Explanation: Ionization energy decreases down the group. Lithium is the smallest alkali
metal and is at the top of the group, so it requires the most energy to remove its valence
electron.
4. The metallic character of alkali metals down the group:
A) Decreases
B) Increases
C) Remains constant
D) Shows no specific trend
Correct Answer: B
Explanation: Metallic character is the tendency to lose electrons. As ionization energy
decreases down the group, it becomes easier to lose electrons, thus increasing metallic
character.
5. Which alkali metal exhibits the lowest electronegativity?
A) Lithium
B) Sodium
C) Potassium
D) Cesium
Correct Answer: D
Explanation: Electronegativity is the tendency to attract shared electrons. As atomic size
increases down the group, the attraction for both its own and shared electrons decreases,
making Cesium the least electronegative.
6. Which of the following alkali metals is an exception to the general density trend in Group
1?
A) Lithium
B) Sodium
C) Potassium
D) Rubidium
Correct Answer: C
Explanation: While density generally increases down the group, Potassium is an exception
as it is less dense than Sodium.
7. Alkali metals are stored under kerosene or paraffin oil because:
A) They are highly soluble in water.
B) They are highly reactive with air and moisture.
C) They have very low melting points.
D) They are radioactive.
Correct Answer: B
Explanation: Their extreme reactivity with oxygen and water vapor in the air necessitates
storage in inert, non-reactive media like kerosene.
8. When lithium is burned in excess air, the major product formed is:
A) Li_2O_2 (lithium peroxide)
B) LiO_2 (lithium superoxide)
C) Li_2O (lithium oxide)
D) Li_3N (lithium nitride)
Correct Answer: C
Explanation: Lithium is unique among alkali metals in predominantly forming a normal oxide
(Li_2O) when reacting with oxygen.
9. Burning sodium in excess oxygen predominantly forms:
A) Normal oxide
B) Peroxide
C) Superoxide
D) Hydroxide
Correct Answer: B
Explanation: Sodium forms sodium peroxide (Na_2O_2) upon combustion in excess oxygen.
10. Which alkali metal forms a superoxide when burned in excess oxygen?
A) Lithium
B) Sodium
C) Potassium
D) Both B and C
Correct Answer: C
Explanation: Potassium, Rubidium, and Cesium form superoxides (MO_2) when burned in
excess oxygen. Lithium forms normal oxide, and Sodium forms peroxide.
11. The reaction of alkali metals with water is highly exothermic, producing hydrogen gas
and:
A) Metal oxides
B) Metal hydrides
C) Metal hydroxides
D) Metal carbonates
Correct Answer: C
Explanation: The general reaction is 2M(s) + 2H_2O(l) \rightarrow 2MOH(aq) + H_2(g),
where MOH is a strong base (metal hydroxide).
12. Which alkali metal reacts most violently with water?
A) Lithium
B) Sodium
C) Potassium
D) Cesium
Correct Answer: D
Explanation: Reactivity with water increases significantly down the group due to decreasing
ionization energy, making Cesium the most reactive.
13. The color observed in the flame test for Sodium (Na) is:
A) Crimson Red
B) Golden Yellow
C) Lilac (Pale Violet)
D) Blue-violet
Correct Answer: B
Explanation: Sodium compounds impart a characteristic intense golden yellow color to a
flame.
14. The decreasing order of melting points for alkali metals is:
A) Cs > Rb > K > Na > Li
B) Li > Na > K > Rb > Cs
C) Na > Li > K > Rb > Cs
D) Li > K > Na > Rb > Cs
Correct Answer: B
Explanation: Melting points decrease down the group due to the weakening of metallic
bonds as atomic size increases.
15. Alkali metals are generally good conductors of electricity because:
A) They have high ionization energies.
B) They form stable ionic bonds.
C) They have loosely held, delocalized valence electrons.
D) They have high electronegativity.
Correct Answer: C
Explanation: The single valence electron in each atom is delocalized, forming a "sea of
electrons" that allows for easy electrical conduction.
16. Which of the following statements about alkali metals is FALSE?
A) They are strong reducing agents.
B) They have low densities.
C) Their metallic character increases down the group.
D) Their reactivity with water decreases down the group.
Correct Answer: D
Explanation: Their reactivity with water increases down the group due to lower ionization
energies and larger atomic sizes making electron loss easier.
17. The oxidation state of hydrogen in alkali metal hydrides (MH) is:
A) +1
B) -1
C) 0
D) +2
Correct Answer: B
Explanation: In alkali metal hydrides, hydrogen is more electronegative than the metal and
exists as a hydride ion (H^-).
18. Which alkali metal is the strongest reducing agent in aqueous solution?
A) Sodium
B) Potassium
C) Lithium
D) Cesium
Correct Answer: C
Explanation: Despite having a higher ionization energy than other alkali metals, Lithium's
exceptionally high hydration energy (due to the small size of Li^+ ion) makes it the strongest
reducing agent in aqueous solution.
19. The reason for the high reducing power of lithium in aqueous solution is its:
A) Lowest ionization energy.
B) Largest atomic size.
C) Exceptionally high hydration energy of Li^+ ion.
D) Highest electronegativity.
Correct Answer: C
Explanation: The large energy released during the hydration of the small Li^+ ion
compensates for its higher ionization energy, making the overall process highly favorable.
20. When an alkali metal reacts with a halogen, the product formed is:
A) Covalent halide
B) Metallic bond
C) Ionic halide
D) Hydrogen bond
Correct Answer: C
Explanation: Alkali metals (highly electropositive) readily transfer their single valence
electron to halogens (highly electronegative) to form ionic bonds and thus ionic halides.
21. Which alkali metal imparts a crimson red color to the flame?
A) Sodium
B) Potassium
C) Lithium
D) Rubidium
Correct Answer: C
Explanation: Lithium compounds produce a distinct crimson red color in a flame test.
22. What is the common characteristic of all alkali metals regarding their valence shell?
A) All have 2 valence electrons.
B) All have a completely filled valence shell.
C) All have 1 electron in their outermost s-orbital.
D) All have 7 valence electrons.
Correct Answer: C
Explanation: This single valence s-electron defines them as Group 1 elements and dictates
much of their chemistry.
23. The reactivity of alkali metals with hydrogen to form hydrides generally:
A) Increases down the group.
B) Decreases down the group.
C) Remains constant.
D) Is unpredictable.
Correct Answer: B
Explanation: While the metallic character increases, the stability of the ionic hydride bond
(M^+H^-) becomes less favorable as the M^+ ion becomes larger and its charge density
decreases, leading to weaker ionic attraction.
24. Among the alkali metals, which one requires the least amount of energy to lose its
valence electron?
A) Lithium
B) Sodium
C) Potassium
D) Cesium
Correct Answer: D
Explanation: This refers to the lowest first ionization energy, which is characteristic of
Cesium due to its largest atomic size and weakest nuclear attraction to the valence electron.
25. The basicity of alkali metal hydroxides (MOH):
A) Decreases down the group.
B) Increases down the group.
C) Remains constant.
D) Is not related to metallic character.
Correct Answer: B
Explanation: As metallic character increases down the group, the M-O bond becomes more
ionic and weaker, allowing easier dissociation of OH^- ions, thus increasing basicity.
26. Which of the following is NOT a property of alkali metals?
A) Highly electropositive.
B) Form basic oxides.
C) High ionization energies.
D) Good reducing agents.
Correct Answer: C
Explanation: Alkali metals are known for their low ionization energies, which is why they
readily lose electrons and are highly reactive.
27. The metallic bond strength in alkali metals:
A) Increases down the group.
B) Decreases down the group.
C) Remains constant.
D) Shows no specific trend
Correct Answer: B
Explanation: As atomic size increases down the group, the valence electrons are further
from the nucleus, leading to weaker attraction and thus weaker metallic bonding.
28. The products of the reaction between Potassium and water are:
A) KO and H_2O
B) KOH and H_2
C) K_2O_2 and H_2
D) KH and O_2
Correct Answer: B
Explanation: Alkali metals react with water to produce a metal hydroxide and hydrogen gas:
2K(s) + 2H_2O(l) \rightarrow 2KOH(aq) + H_2(g).
29. Which alkali metal's flame test color is best observed through cobalt blue glass?
A) Lithium
B) Sodium
C) Potassium
D) Cesium
Correct Answer: C
Explanation: Cobalt blue glass is used to filter out the intense yellow light from trace sodium
impurities, allowing the faint lilac (pale violet) color of potassium to be seen.
30. Which of the following is true regarding alkali metals' density?
A) All alkali metals are denser than water.
B) Sodium is denser than potassium.
C) Lithium is the densest alkali metal.
D) Cesium is the least dense alkali metal.
Correct Answer: B
Explanation: Sodium (0.97 \ g/cm^3) is denser than Potassium (0.86 \ g/cm^3), which is the
exception to the increasing density trend. Li, Na, and K are all less dense than water (1.0 \
g/cm^3).
31. The ability of an alkali metal to lose an electron is best described by its:
A) Electronegativity
B) Electron affinity
C) Ionization energy
D) Atomic mass
Correct Answer: C
Explanation: Ionization energy is the direct measure of the energy required to remove an
electron from an atom.
32. What type of bond is formed when alkali metals react with halogens?
A) Covalent bond
B) Metallic bond
C) Ionic bond
D) Hydrogen bond
Correct Answer: C
Explanation: The large difference in electronegativity between the electropositive alkali
metals and electronegative halogens results in the formation of ionic bonds.
33. Alkali metals are stored in kerosene to prevent reaction with:
A) Nitrogen
B) Carbon dioxide
C) Oxygen and moisture
D) Other alkali metals
Correct Answer: C
Explanation: Kerosene acts as a barrier, preventing contact with atmospheric oxygen and
water vapor, which would react vigorously with the metals.
34. Which of the following is an incorrect match of alkali metal with its characteristic flame
color?
A) Lithium - Crimson Red
B) Sodium - Golden Yellow
C) Potassium - Blue-violet
D) Cesium - Blue-violet
Correct Answer: C
Explanation: Potassium produces a lilac (pale violet) flame. Cesium gives a blue-violet
flame.
35. The stability of alkali metal hydrides (MH) generally:
A) Increases down the group.
B) Decreases down the group.
C) Remains constant.
D) Is not predictable.
Correct Answer: B
Explanation: As the cation size increases down the group, the charge density decreases,
leading to weaker electrostatic attraction with the small hydride ion and thus less stable
hydrides.
36. All alkali metals react with water to form:
A) Acidic solutions
B) Neutral solutions
C) Strongly basic solutions
D) Amphoteric solutions
Correct Answer: C
Explanation: The metal hydroxides (MOH) formed are all strong bases, making the resulting
solutions strongly alkaline.
37. Which of the following elements is classified as an s-block element but is NOT an alkali
metal?
A) Lithium
B) Sodium
C) Hydrogen
D) Potassium
Correct Answer: C
Explanation: Hydrogen has a 1s^1 configuration like alkali metals but is a non-metal with
very different chemical and physical properties.
38. The property of alkali metals that makes them strong reducing agents is their:
A) High electronegativity.
B) Small atomic size.
C) Low ionization energy.
D) High melting point.
Correct Answer: C
Explanation: Good reducing agents readily lose electrons. Alkali metals have very low
ionization energies, making them excellent electron donors.
39. The reaction of alkali metals with oxygen at room temperature results in:
A) Slow rusting
B) Tarnish
C) Explosive combustion
D) Formation of peroxides only
Correct Answer: B
Explanation: Even at room temperature, they rapidly react with oxygen to form a thin oxide
layer, losing their metallic luster (tarnishing).
40. As we move down Group 1, the tendency to form stable M^+ ions:
A) Increases
B) Decreases
C) Remains constant
D) First decreases then increases
Correct Answer: A
Explanation: With decreasing ionization energy, the ease of losing the valence electron
increases, leading to a greater tendency to form stable M^+ ions.
41. Which statement is true regarding the density of Lithium (Li) compared to water?
A) Li is denser than water.
B) Li is less dense than water.
C) Li has the same density as water.
D) Li's density varies with temperature.
Correct Answer: B
Explanation: Lithium has a density of 0.53 \ g/cm^3, which is less than water's density of 1.0
\ g/cm^3, so it floats.
42. What is the primary reason for the high reactivity of alkali metals?
A) They have a strong nuclear charge.
B) They are able to form multiple bonds.
C) They readily lose their single valence electron.
D) They have high electron affinities.
Correct Answer: C
Explanation: The ease with which they can achieve a stable noble gas configuration by
losing their sole valence electron drives their high reactivity.
43. Which of the following alkali metal oxides is correctly matched with its type formed by
burning in excess oxygen?
A) Li - Peroxide
B) Na - Superoxide
C) K - Normal oxide
D) Cs - Superoxide
Correct Answer: D
Explanation: Lithium forms normal oxide (Li_2O), Sodium forms peroxide (Na_2O_2), and
Potassium, Rubidium, and Cesium form superoxides (MO_2).
44. The products of the reaction of Sodium with dilute HCl are:
A) Na_2O and H_2
B) NaCl and H_2O
C) NaCl and H_2
D) Na_2O and Cl_2
Correct Answer: C
Explanation: Alkali metals react violently with acids to produce a salt and hydrogen gas:
2Na(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_2(g).
45. The property that decreases down the group for alkali metals is:
A) Atomic radius
B) Metallic character
C) First ionization energy
D) Reactivity with water
Correct Answer: C
Explanation: Atomic radius, metallic character, and reactivity with water all increase down
the group. First ionization energy decreases.
46. Which statement accurately describes the metallic bond in alkali metals?
A) It strengthens down the group.
B) It weakens down the group due to larger ion size.
C) It is a covalent bond.
D) It involves strong directional forces.
Correct Answer: B
Explanation: As the atomic size increases, the positive nuclei are further apart from each
other and the delocalized electron sea, leading to a weaker overall metallic attraction.
47. Why are alkali metals excellent electrical conductors?
A) They have strong ionic bonds.
B) Their electrons are tightly bound to the nucleus.
C) They have delocalized valence electrons.
D) They have a crystalline structure.
Correct Answer: C
Explanation: The freedom of movement of the delocalized valence electrons allows for
efficient charge transfer, making them good conductors.
48. The flame color of Potassium is often obscured by Sodium contamination. How can this
be overcome?
A) By adding more Potassium.
B) By heating more strongly.
C) By observing through cobalt blue glass.
D) By using a colder flame.
Correct Answer: C
Explanation: Cobalt blue glass selectively filters out the intense yellow light from sodium,
allowing the less intense lilac (pale violet) color of potassium to be observed.
49. Which of the following is the least reactive alkali metal?
A) Cesium
B) Rubidium
C) Potassium
D) Lithium
Correct Answer: D
Explanation: Reactivity increases down Group 1. Therefore, Lithium, being at the top, is the
least reactive among the alkali metals.
50. The basic strength of the hydroxides of alkali metals (MOH) from Li to Cs:
A) Increases
B) Decreases
C) Remains constant
D) First increases then decreases
Correct Answer: A
Explanation: As you go down the group, the ionic character of the M-O bond increases and
the bond strength decreases, leading to easier dissociation of OH^- and thus stronger
basicity.
MDCAT 2025 - Biology MCQs (Endoplasmic Reticulum & Golgi Complex ONLY)
Instructions: Choose the best option for each question.
1. Which organelle is a continuous network of membranes extending throughout the
cytoplasm, directly connected to the outer nuclear envelope?
A) Golgi apparatus
B) Lysosome
C) Mitochondrion
D) Endoplasmic reticulum
Correct Answer: D
Explanation: The ER is a vast network of interconnected membranes that extends from the
outer nuclear membrane into the cytosol.
2. Ribosomes are found attached to the surface of which part of the endoplasmic reticulum?
A) Smooth ER
B) Rough ER
C) Sarcoplasmic reticulum
D) Both A and B
Correct Answer: B
Explanation: The "rough" appearance of the RER is due to the presence of ribosomes on its
cytoplasmic surface, responsible for synthesizing proteins destined for the ER or beyond.
3. Proteins destined for secretion from the cell are primarily synthesized on ribosomes
located on the:
A) Free ribosomes in the cytoplasm
B) Smooth endoplasmic reticulum
C) Rough endoplasmic reticulum
D) Golgi apparatus
Correct Answer: C
Explanation: Ribosomes on the RER synthesize proteins that are destined for secretion,
insertion into membranes, or delivery to certain organelles like lysosomes.
4. Which function is primarily associated with the Smooth Endoplasmic Reticulum (SER)?
A) Protein folding
B) Lipid synthesis
C) Glycosylation of proteins
D) Disulfide bond formation
Correct Answer: B
Explanation: