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emperature increase hecause the hear energy is used t (A) break covalent honds w

ID: 699232 • Letter: E

Question

emperature increase hecause the hear energy is used t (A) break covalent honds within the molecules (8) break inemlecular Seces betwceem molecules (O increase the velcity of the molecules (D) rearrange atms within the molecules t The reaction CHig)-2gis (A) exohenmic hecause breaking hond's requires energy (B) exothermic because breaking honds releases energy O endothermic because breaking honds requires enerngy D) endothermic because breaking honds releases energy 69. What is the change inBond Dissociation Energy enthalpy for this reaction? 351 800 1070 142 499 0-0 (A)-1039 (C) 561 k (B) -561 k (D) 1039 k 70. The density of water at 100 °C is 0.9584 gmL A student performed three trial measurements to determine the density of water at 100 C and obtained the results shown. Which term(s) best describe these measurements? Trial Density mL-- I 0.9141 2 09991 3 08911 (B) precise (A) accurate (C) neither precise nor accurate (D) both precise and accurate

Explanation / Answer

67. answer: B (to sperate molecules . we need to overcome intermolcular forces)

68. answer: c ( to break the bonds it consumes energy.it is endothermic)

69. DH = (2*1070+1*499)+(2*-800) = 1039 kj

answer: D

70. answer: C, neither precise nor accurate.