Which of the following contains a coordinate bond?
A. NaCl
B. H₂O
C. NH₃
D. O₃
Answer: Option D
Solution (By JKSSB Mock Tests)
Ozone (O₃) has a coordinate bond (dative bond). One oxygen atom donates a lone pair to another oxygen atom. The Lewis structure shows O=O⁺–O⁻ or resonance. NaCl is ionic; H₂O has polar covalent bonds; NH₃ has ordinary covalent bonds (though it can donate a lone pair to form coordinate bond in NH₄⁺).
Assertion (A): The first ionization energy of Nitrogen is higher than that of Oxygen. Reason (R): Nitrogen has a half-filled p-orbital which is exceptionally stable.
A.A is true but R is false.
B.Both A and R are true but R is NOT the correct explanation of A.
C.Both A and R are true and R is the correct explanation of A.
Explanation:
Nitrogen (1s2 2s2 2p3) has a exactly half-filled p-subshell, which confers extra stability due to symmetry and exchange energy. Oxygen (1s2 2s2 2p4) has one paired electron in the p-orbital, leading to electron-electron repulsion, making it easier to remove. Thus, N has a higher IE than O. Both are true and R explains A.
Explanation:
Bakelite (phenol-formaldehyde resin) is thermosetting; once molded, it cannot be reshaped by heating. Polythene, nylon, PVC are thermoplastics, which can be repeatedly softened by heat.
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