Other Chemistry Answers

13 What is the boiling point of ethanol at 720 mm Hg when its normal point at 760 mm Hg is known to be 78.3 o C

75.3oC
75.3oC

76.3oC
76.3oC

−3oC
−3oC

−2oC
−2oC
14 Which of these best describes a phenomenon whereby a solid suddenly shrinks before melting?
Sublimation
Shrinking
Sintering
Evaporation
15 How many layers are usually formed in a separating funnel?
4
3
2
1

10 Which of the following is helpful in establishing the purity of a compound?
Boiling point
Sublimation point
Decomposition point
All of the above
11 The phenomenon whereby solids pass directly from the solid state to the gaseous state is termed ___________
Sublimation
Evaporation
Fractional distillation
Recrystallization
12 Mercury is traded by the "flask", a unit that has a mass of 34.5 kg. What is the volume of a flask of mercury if the density of mercury is 13.6 g/ml?
200 ml
2350 ml
2537 ml
1970 ml

7 Freezing points are difficult to determine because of the phenomenon of ___________
Impurities
Refridgeration
Supercooling
None of the above
8 What is the meaning of "oiling out" during recrystallization?
Compound melts before dissolving
Compound dissolves before melting
Compound turns to oil
Compound sublimes
9 Insoluble impurities have ______________ effect on the melting pont.
little
no
maximum
minimum

4 Which of these properties is considered during recrystallization process?
Temperature
Mass
Volume
Density
5 A cube of copper was found to have a mass of 630 g. What are the dimensions of the cube given the density of copper to be 8.94 g/cm3.
70.47 cm
8.39 cm
4.13 cm
8.26 cm
6 Why is ethanol not a suitable solvent for extracting aqueous solutions?
Due to its high boiling point
Due to its solubility in water
Due to its flammability
All of the above

1 The principal purpose of extraction is ___________.
To recover a substance from a mixture
To sublime a substance
To activate a substance
None of the above
2 The boiling point of methanol is ______________.

65oC
65oC

78oC
78oC

97oC
97oC

69oC
69oC
3 Which equipment can be used for a fire?
Band-aid
Fire quencher
Fire blanket
Fire extinguisher

19 An isomer of pentane is ___________.
2,2-Dimethylpropane
2,2-Dimethylpentane
1,1-Dimethylcyclopropane
2,3-Dimethylbutane
20 Isomers have the same _____________.
Melting point
Molecular formula
Boiling point
Reactivity

16 Ethyne gas may be tested for saturation in the laboratory. Which of these is a positive test?
It changes the colour of cobalt chloride paper from blue to pink
It changes the colour of bromine water from red to blue
It turns lime water milky
It decolorizes acidified potassium permanganate solution.
17 Which molecule contains a total of three carbon atoms?
2-methyl propane
2-methyl butane
Propane
Butane
18 Breaking of a larger hydrocarbon molecule into a smaller one by heating in the presence of a catalyst is called ___.
Cracking
Orthofugation
Centrifugation
Thermogenation

13 What is the expected product formed from the reaction between 2-butene and chlorine?
1-chlorobutane
2,2-dichlorobutane
2-chlorobutane
2,3-dichlorobutane
14 The representation
CH3−CH2−CH2−CH2−CH3
CH3−CH2−CH2−CH2−CH3
for the alkane pentane is an example of ____________
a molecular formula
a condensed structural formula
an expanded structural formula
a skeletal structural formula
15 Which of these statements is true?
Ethyne will dissolve in water and cyclohexane
Ethyne will dissolve in water and dilute hydrochloric acid
Ethyne will dissolve in cyclohexane and methyl benzene
All of the above

10 Which of these compounds is an organic acid?

CH3OCH3
CH3OCH3

CH3OH
CH3OH

CH3COOH
CH3COOH

CH3COOCH3
CH3COOCH3
11 What happens when bromine water is added to a saturated hydrocarbon and an unsaturated hydrocarbon?
There is no change with either hydrocarbon
Both hydrocarbons change the bromine water from colourless to brown
The saturated hydrocarbon changes the bromine water from brown to colourless
The unsaturated hydrocarbon changes the bromine water from brown to colourless.
12 Which of the following will undergo an addition reaction with chlorine?
Butane
Pent-2-ene
Benzene
Butanoic acid

7 In a molecule of
CH4
CH4
, the hydrogen atoms are spatially oriented towards the center of a regular ___________
Tetrahedron
Pyramid
Rectangle
Square
8 In which pair of hydrocarbons does each compound contain only one double bond per molecule?

C2H2
C2H2
and
C2H6
C2H6

C2H2
C2H2
and
C3H6
C3H6

C4H8
C4H8
and
C2H4
C2H4

C6H6
C6H6
and
C7H8
C7H8
9 Which element is present in all organic compounds?
Nitrogen
Oxygen
Carbon
Phosphorus