Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.
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Question 761: In countries where the temperature falls below 273K, salt is always sprinkled on the icy road in order to
Options:
A) lower the melting point of the ice
B) increase the density of the ice
C) make the ice impure
D) raise the melting point of the ice
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The correct answer is A .
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Question 762: what is the pH of 0.00lmoldm3 solution of sodium hydroxide
Options:
A) 14
B) 13
C) 12
D) 11
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The correct answer is D .
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Question 763: Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises?
Options:
A) The bonds in the reacting molecules are more readily broken
B) The molecular collisions become more violent
C) A lower proportion of the molecules has the necessary minimum energy to react
D) The collision frequency of the molecules increase
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The correct answer is D .
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Question 764: The density of a certain gas is 1.98gdm-3 at s.t.p. What is the molecular mas of the gas?
Options:
A) 44.0 g
B) 54.0 g
C) 26.0 g
D) 31.0 g
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The correct answer is A .
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Question 765:
The IUPAC name of the compound CFCHBrCl is
Options:
A) 2-chloro-2-bromo-1,1,1-trifluoroethane
B) 2-bromo-2-chloro-1,1,1-trifluoroethane
C) 1-bromo-1-chloro-2,2,2-trifluoroethane
D) 1,1,1-trifluoro-2-bromo-2-chloroethane
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The correct answer is B .
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Question 766:
Use the above option to answer this question. The dehydration of ammonium salt of alkanoic acids produces a compound with the general formula
Options:
A) A
B) B
C) C
D) D
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The correct answer is B .
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Question 767: Which of the following ions require the largest quantity of electricity for discharge at an electrode?
Options:
A) 4.0 moles of Cl-
B) 3.0 moles of Na+
C) 2.5 moles of Cu2+
D) 2.0 moles of Al3+
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The correct answer is C .
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Question 768:
Which of the following alkanes has a straight-chain structure?
Options:
A) Cyclopentane (C5H10)
B) Isobutane (C4H10)
C) 2 - methyl propane (C4H10)
D) Pentane (C5H12)
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The correct answer is D .
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Question 769: Zinc and carbon rods are used as anode and cathode respectively in a
Options:
A) Leclanche cell
B) lead accumulator
C) Daniel cell
D) voltaic cell
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The correct answer is A .
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Question 770: The best way of collecting chlorine is?
Options:
A) by downward displacement of air
B) by upward displacement of air
C) over water
D) under water
E) over mercury
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The correct answer is B .