Which of the following species is isoelectronic with CO?
A. O2
B. NO
C. N2
D. CO2
Answer: Option C
Solution (By JKExamLibrary)
Isoelectronic species have the same total number of electrons. Carbon monoxide (CO) has 6 (from C) + 8 (from O) = 14 electrons. Nitrogen molecule (N2) has 7 + 7 = 14 electrons. Therefore, N2 is isoelectronic with CO. O2 has 16, CO2 has 22, and NO has 15 electrons.
Explanation:
Iodine sublimes on heating, converting to vapor, leaving sand behind. Iodine vapors can be condensed. Filtration cannot separate two solids; distillation for liquids.
Assertion (A): Covalent compounds generally have low melting points. Reason (R): The intermolecular forces in covalent compounds are weak compared to ionic compounds.
A.A is false but R is true.
B.A is true but R is false.
C.Both A and R are true but R is NOT the correct explanation of A.
D.Both A and R are true and R is the correct explanation of A.
Explanation:
Covalent compounds consist of molecules held together by weak van der Waals forces, unlike the strong electrostatic forces in ionic lattices. Therefore, less heat energy is required to break these intermolecular forces, resulting in low melting and boiling points. Both statements are true and R correctly explains A.
Explanation:
Graphite's layered structure with weak van der Waals forces between layers allows them to slide over each other, making it a good dry lubricant. It is used in machines where oil cannot be used (high temperature) or in pencil lead mixed with clay. Diamond is hard, used as abrasive. Fullerenes are nanomaterials, not lubricants. Coal is fuel.
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