Diamond and graphite are allotropes of carbon. The difference arises because of:
A. Different chemical composition
B. Presence of impurities
C. Different number of protons
D. Different arrangement of atoms
Answer: Option D
Solution (By JKExamLibrary)
Allotropes are different structural forms of the same element. Diamond has a tetrahedral sp³ network, while graphite has a planar sp² layered structure. This difference in atomic arrangement results in distinct physical properties: diamond is hard, transparent, insulating; graphite is soft, black, conducting. Allotropes have same chemical composition (pure carbon). Other allotropes include fullerenes and graphene.
Explanation:
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:
Graham's law: r₁/r₂ = √(M₂/M₁). Given rA/rB = 1/2, so √(MB/MA) = 1/2. Squaring: MB/MA = 1/4 => MB = MA/4 = 64/4 = 16 g/mol. B is lighter and diffuses faster. Logical check: rate inversely proportional to square root of molar mass; if rate is double, mass is quarter. Answer is 16.
Explanation:
Total electrons = 16 (Sulfur). Period = number of shells = 3. Valence electrons = 6, group = 10+6 = 16 (Group 16, chalcogens). Group 6 would be 6 valence electrons but in d-block, not applicable. Group 18 has 8 valence electrons (except He). So sulfur is in group 16, period 3.
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