Download Chapter 2 - Atoms, Molecules, and Ions

Chapter 2 - Atoms, Molecules, and Ions
chemistry history, Dalton’s atomic theory, nomenclature
A (Applied) 97-2. How many hydrogen atoms are present in 2.0 moles of ethanol, C2H5OH?
A. 6.0 x 1023
B. 1.2 x 1024
C. 3.6 x 1024
D. 7.2 x 1024
A 97-4. A hydrocarbon contains 81.8% by mass. What is the empirical formula of this
hydrocarbon?
A. C3H8
B. C2H3
C. CH3
D. CH2
A 96-1. Which of the following pairs represent(s) an empirical formula followed by a molecular
formula?
I. O2 and O3
II. NO2 and N2O4
III. C2H4 and C4H8
A. II only
B. I and II only
C. II and III only
D. I, II and III only
A 96-2. What is the major difference between an element and a compound?
A. The composition of an element is always the same but the composition of a
compound may change.
B. An element contains atoms but a compound contains molecules.
C. Elements are more reactive than compounds.
D. Compounds can be broken down further but elements cannot.
A 96-4. How many hydrogen atoms are present in 0.020 moles of C2H6?
A. 1.2 x 1022
B. 7.2 x 1022
C. 6.0 x 1023
A 95-1.
D. 3.6 x 1024
The relative molar mass of magnesium nitrate, Mg(NO3)2 is closest to which of the
numbers below?
A. 90
B. 130
C. 150
D. 170
A 95-2. Which type(s) of formula can be determined by using only the percent composition
data for an unknown compound?
I. Empirical (simplest) formula
II. Molecular formula
A. I only
B. II only
C. Both I and II
D. Neither I nor II
A 95-3. What is the total number of atoms in 0.01 moles of ammonium sulphate (NH 4)2SO4?
A. 6.02 x 1023
B. 9.03 x 1022 C. 1.81 x 1022 D. 6.02 x 1021
A 94-3. The mass percentage of oxygen in sulphur trioxide, SO 3, is closest to
A. 25%
B. 30%
C. 60%
D. 75%
A 94-10. How many hydrogen atoms are contained in 6.4 grams of CH3OH (relative molecular
mass = 32)?
A. 1.2 x 1023
B. 4.8 x 1023
C. 6.0 x 1023
D. 2.4 x 1024
A 93-2. The empirical formula for a certain compound is C2H3O2 and its relative molar mass is
120  5 g mol-1. What is its molecular formula?
A. C6H9O6
B. C6H9O3
C. C4H6O4
D. C2H3O2
A 93-4. Titanium (Relative Atomic Mass=48) reacts with oxygen to form titanium oxide, TiO 2.
How many grams of TiO2 can be prepared from 7.2 g titanium and 7.2 g oxygen?
A. 6.3
B. 9.6
C. 12.0
D. 14.4
A 92-1. Which of the following statements is (are) true about the molecular formula of a
substance?
I. It is sometimes equal to the empirical formula.
II. It is always a whole number multiple of the empirical formula
III. It indicates the exact number and the identities of the atoms that make
up a molecule.
A. I only
B. II only
C. I and II only
D. I, II, and III
A 92-2. How many atoms are in 12 molecules of glucose, C6H12O6?
A. 24
B. 288
C. 7.22 x 1024
D. 1.73 x 1026
A 92-3. The simplest formula for an oxide of nitrogen that has 25.9 percentage nitrogen by mass
is:
A. N2O
B. NO2
C. N2O3
D. N2O5
A 91-1. Which of the following molecular formulae might also be an empirical formula?
A. N2F4
B. C7H8
C. C3H6O3
D. P4
A 91-2. The relative molecular mass of a certain compound is 84. How many molecules are
there in 1.68 grams of this compound?
A. 1.2 x 1022 B. 1.2 x 1023
C. 6.0 x 1023
D. 3.0 x 1025
G (general) 93-1. The relative atomic mass of the element boron is not a whole number because
A. it cannot be obtained in a pure state.
B. some of its atoms have different numbers of protons.
C. some of its atoms have different numbers of neutrons.
D. some of its atoms have different numbers of electrons.
G 93-2. In 1928, 1.0 g of the element rhenium, Re, was isolated from 660 kg of the ore
molybdenite. The percentage by mass of this element in the molybdenite was
A. 0.15 %
B. 6.6 x 10-3 % C. 3.5 x 10-4 % D. 1.5 x 10-4 %
G 93-4. How many moles of chlorine gas are present in 103.0 g of chlorine?
A. 1.45
B. 6
C. 5
D. 4
45.The alkenes are compounds of carbon and hydrogen with the general formula CnH2n. If
0.561 gram of any alkene is burned in excess oxygen, what number of moles of H 2O is
formed?
(A) 0.0400 mole
(B) 0.0600 mole (C) 0.0800 mole (D) 0.400 mole (E) 0.800 mole
33.Which of the following conclusions can be drawn from J. J. Thomson’s cathode ray
experiments?
a. Atoms contain electrons.
b. Practically all the mass of an atom is contained in its nucleus.
c. Atoms contain protons, neutrons, and electrons.
d. Atoms have a positively charged nucleus surrounded by an electron cloud.
e. No two electrons in one atom can have the same four quantum numbers.
67.Substances X and Y that were in a solution were separated in the laboratory using the
technique of fractional crystallization. This fractional crystallization is possible because
substances X and Y have different
(A) boiling points
(B)
melting points
(C) densities
(D) crystal colors
(E) solubilities