Here below some basic MCQ’s about “Boron, Carbon and Nitrogen” with answer which is explained in details. Let’s check one by one which is given below.
Q1. Which of the following is the most abundant element of Group 13 in Earth’s crust?
A) Boron
B) Aluminium
C) Gallium
D) Indium
Answer: B) Aluminium
Explanation: Aluminium is the most abundant metal in the Earth’s crust, making up about 8% by weight. Boron, although significant, is much less abundant. Gallium and indium are even rarer in comparison.
Q2. Which of the following oxides of boron is acidic?
A) B₂O₃
B) Al₂O₃
C) Ga₂O₃
D) In₂O₃
Answer: A) B₂O₃
Explanation: Boron forms acidic oxides (B₂O₃) due to its high electronegativity and small size. In contrast, aluminium and the heavier members (Ga, In) of Group 13 form amphoteric or basic oxides.
Q3. Boron forms covalent compounds, whereas aluminium forms ionic compounds because:
A) Boron has a larger atomic size.
B) Boron has higher electronegativity and ionization enthalpy.
C) Boron has a higher metallic character.
D) Boron forms stronger metallic bonds.
Answer: B) Boron has higher electronegativity and ionization enthalpy.
Explanation: Boron, being a small atom with high electronegativity and ionization energy, tends to form covalent bonds. Aluminium, being larger and less electronegative, can more easily lose electrons to form ionic bonds.
Q4. Which of the following elements of Group 14 shows the maximum tendency to catenate?
A) Carbon
B) Silicon
C) Germanium
D) Tin
Answer: A) Carbon
Explanation: Carbon exhibits the maximum ability to form long chains (catenation) due to its small atomic size and strong C-C bonds. As we go down the group, the catenation tendency decreases because of weaker bonds between heavier atoms.
Q5. The stability of +2 oxidation state increases down the group in Group 14 elements due to:
A) Inert pair effect
B) Decreasing electronegativity
C) Increase in atomic size
D) Increase in metallic character
Answer: A) Inert pair effect
Explanation: The inert pair effect refers to the reluctance of the s-electrons to participate in bonding. As we move down the group, this effect becomes more prominent, stabilizing the +2 oxidation state, particularly in lead (Pb).
Q6. Which of the following compounds is the strongest reducing agent?
A) SnCl₂
B) PbCl₂
C) GeCl₂
D) SiCl₄
Answer: A) SnCl₂
Explanation: Tin (Sn) in the +2 oxidation state is more stable than lead (Pb) due to the inert pair effect, making SnCl₂ a strong reducing agent.
Nitrogen Family (Group 15)
Q7. The allotropy of phosphorus is due to:
A) Different hybridization
B) Difference in atomic size
C) Difference in molecular structure
D) Variation in oxidation state
Answer: C) Difference in molecular structure
Explanation: Phosphorus exists in different allotropic forms like white, red, and black phosphorus. These forms arise due to different molecular structures rather than changes in hybridization or oxidation states.
Q8. The anomalous behavior of nitrogen compared to other elements of Group 15 is primarily due to:
A) Its small size
B) High electronegativity
C) Non-availability of d-orbitals
D) All of the above
Answer: D) All of the above
Explanation: Nitrogen is unique among the Group 15 elements because of its small atomic size, high electronegativity, and the absence of d-orbitals in its valence shell. This leads to different chemical behavior compared to heavier elements like phosphorus and arsenic.
Q9. Which of the following elements of Group 15 shows the highest metallic character?
A) Nitrogen
B) Phosphorus
C) Arsenic
D) Bismuth
Answer: D) Bismuth
Explanation: As we move down Group 15, metallic character increases due to the larger atomic size and lower ionization energy. Nitrogen is a non-metal, while bismuth is the most metallic element in this group.
Q10. Nitric oxide (NO) is different from other oxides of nitrogen because it:
A) Is paramagnetic
B) Is diamagnetic
C) Forms colored solutions
D) Exists in dimeric form
Answer: A) Is paramagnetic
Explanation: Nitric oxide (NO) has an odd number of electrons, making it paramagnetic. Other oxides of nitrogen, like N₂O and NO₂, either have even numbers of electrons or exist in different forms that lead to diamagnetism.
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