Liquids and Solids | First Year Chemistry Past Paper MCQs | mosaicbro.com

Liquids and Solids | First Year Chemistry Past Paper MCQs

7 of 53 questions (Page 6 of 8)

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36 Heat change for one mole of solid converting into liquid is called:
Correct Answer: C
Explanation: Molar heat of fusion (ΔH_fus) is the energy for solid → liquid transition.
37 Which does not form a molecular crystal?
Correct Answer: B
Explanation: Graphite is a covalent crystal; others are molecular solids.
38 Evaporation causes:
Correct Answer: A
Explanation: Evaporation absorbs heat from surroundings (endothermic).
39 Diamond and graphite are examples of:
Correct Answer: D
Explanation: Allotropes are different forms of the same element (carbon).
40 Dipole-induced dipole forces are also called:
Correct Answer: B
Explanation: Debye forces arise between permanent and induced dipoles.
41 The size of double helix of DNA is:
Correct Answer: A
Explanation: DNA helix diameter ≈ 20 Å (2 nm).
42 Which statement is incorrect about tetragonal crystal system?
Correct Answer: A
Explanation: Tetragonal has a = b ≠ c; angles = 90° (a=b=c defines cubic).
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