Physical Chemistry
Q. For the reaction: A(g) ⇌ B(g) + C(g), if the concentration of A is increased, what will happen to the equilibrium position?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Depends on temperature
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Solution
According to Le Chatelier's principle, increasing the concentration of a reactant will shift the equilibrium to the right.
Correct Answer: B — Shift to the right
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Q. For which of the following diatomic molecules is the bond order equal to 2?
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Solution
F2 has a bond order of 1, while C2 has a bond order of 2.
Correct Answer: D — F2
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Q. For which of the following molecules is the bond order equal to 0?
A.
He2
B.
H2
C.
Li2
D.
Be2
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Solution
He2 has a bond order of 0, as it has equal bonding and antibonding electrons.
Correct Answer: A — He2
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Q. For which of the following molecules is the molecular orbital diagram similar to that of O2?
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Solution
The molecular orbital diagram of F2 is similar to that of O2, with the same energy level arrangement.
Correct Answer: B — F2
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Q. For which of the following pairs of molecules is the bond order the same?
A.
N2 and C2
B.
O2 and F2
C.
B2 and C2
D.
N2 and O2
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Solution
O2 and F2 both have a bond order of 2.
Correct Answer: B — O2 and F2
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Q. For which value of k does the equation x^2 + kx + 16 = 0 have no real roots?
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Solution
The discriminant must be less than zero: k^2 - 4*1*16 < 0 => k^2 < 64 => k < 8 and k > -8.
Correct Answer: A — -8
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Q. How many atoms are in 2 moles of oxygen gas (O2)?
A.
6.022 x 10^23
B.
1.2044 x 10^24
C.
3.011 x 10^23
D.
12.044 x 10^23
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Solution
Each O2 molecule has 2 oxygen atoms. Number of atoms = moles x Avogadro's number x 2 = 2 moles x 6.022 x 10^23 molecules/mole x 2 = 1.2044 x 10^24 atoms.
Correct Answer: B — 1.2044 x 10^24
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Q. How many grams are in 0.25 moles of glucose (C6H12O6)?
A.
30 g
B.
45 g
C.
75 g
D.
90 g
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Solution
Molar mass of C6H12O6 = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = 0.25 moles x 180 g/mol = 45 g.
Correct Answer: D — 90 g
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Q. How many grams are in 0.25 moles of KCl?
A.
35 g
B.
70 g
C.
17.5 g
D.
140 g
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Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Mass = moles x molar mass = 0.25 moles x 74.5 g/mol = 18.625 g.
Correct Answer: B — 70 g
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Q. How many grams are in 0.25 moles of sulfuric acid (H2SO4)?
A.
49 g
B.
98 g
C.
24.5 g
D.
12.25 g
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Solution
Molar mass of H2SO4 = 98 g/mol. Mass = moles x molar mass = 0.25 moles x 98 g/mol = 24.5 g.
Correct Answer: A — 49 g
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Q. How many grams are in 0.5 moles of sodium (Na)?
A.
11 g
B.
22 g
C.
5.5 g
D.
44 g
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Solution
The molar mass of sodium is approximately 23 g/mol. Therefore, 0.5 moles of Na weigh 0.5 x 23 g = 11 g.
Correct Answer: A — 11 g
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Q. How many grams are in 2 moles of carbon dioxide (CO2)?
A.
44 g
B.
88 g
C.
22 g
D.
66 g
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Solution
The molar mass of CO2 is 44 g/mol. Thus, 2 moles of CO2 = 2 x 44 g = 88 g.
Correct Answer: B — 88 g
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Q. How many grams are in 3 moles of glucose (C6H12O6)?
A.
180 g
B.
360 g
C.
540 g
D.
90 g
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Solution
Molar mass of glucose = 6*12 + 12*1 + 6*16 = 180 g/mol. Mass = moles x molar mass = 3 moles x 180 g/mol = 540 g.
Correct Answer: B — 360 g
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Q. How many grams of CO2 are produced from the complete combustion of 1 mole of C3H8?
A.
44 g
B.
88 g
C.
132 g
D.
22 g
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Solution
C3H8 + 5O2 → 3CO2 + 4H2O. 1 mole of C3H8 produces 3 moles of CO2. Mass = 3 * 44 g = 132 g.
Correct Answer: B — 88 g
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Q. How many grams of KCl are needed to prepare 0.5 moles of KCl solution?
A.
37.5 g
B.
74.5 g
C.
50 g
D.
100 g
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Solution
The molar mass of KCl is 39 g/mol (K) + 35.5 g/mol (Cl) = 74.5 g/mol. Therefore, 0.5 moles of KCl will weigh 0.5 x 74.5 g = 37.25 g.
Correct Answer: B — 74.5 g
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Q. How many grams of KCl are needed to prepare 0.5 moles of KCl solution? (Molar mass of KCl = 74.5 g/mol)
A.
37.25 g
B.
74.5 g
C.
148.5 g
D.
18.5 g
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Solution
To find the mass, use the formula: mass = moles x molar mass. Thus, 0.5 moles x 74.5 g/mol = 37.25 g.
Correct Answer: A — 37.25 g
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Q. How many grams of KCl are needed to prepare 0.5 moles of KCl?
A.
37.5 g
B.
45 g
C.
50 g
D.
60 g
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Solution
The molar mass of KCl is approximately 74.5 g/mol. Therefore, 0.5 moles of KCl will weigh 0.5 x 74.5 g = 37.25 g.
Correct Answer: B — 45 g
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Q. How many grams of KCl can be produced from the reaction of 10 g of K with excess Cl2?
A.
74.5 g
B.
37.25 g
C.
148.5 g
D.
18.5 g
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Solution
10 g of K = 0.25 moles. K + Cl2 → KCl, so 0.25 moles of KCl = 0.25 * 74.5 g = 18.625 g.
Correct Answer: A — 74.5 g
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Q. How many grams of NaOH are needed to neutralize 1 mole of HCl?
A.
40 g
B.
36.5 g
C.
58.5 g
D.
23 g
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Solution
The reaction between NaOH and HCl is 1:1. The molar mass of NaOH is 40 g/mol, so 1 mole of NaOH is needed, which weighs 40 g.
Correct Answer: C — 58.5 g
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Q. How many grams of NaOH are needed to prepare 0.5 moles of NaOH solution?
A.
20 g
B.
40 g
C.
10 g
D.
30 g
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Solution
The molar mass of NaOH is 40 g/mol. Therefore, to prepare 0.5 moles, you need 0.5 x 40 g = 20 g.
Correct Answer: B — 40 g
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Q. How many grams of NaOH are needed to prepare 0.5 moles of NaOH solution? (Molar mass of NaOH = 40 g/mol)
A.
20 g
B.
40 g
C.
10 g
D.
30 g
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Solution
To find the mass, use the formula: mass = moles × molar mass. Thus, 0.5 moles × 40 g/mol = 20 g.
Correct Answer: A — 20 g
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Q. How many grams of solute are needed to prepare 0.5 L of a 1 M NaCl solution? (Molar mass of NaCl = 58.5 g/mol)
A.
29.25 g
B.
58.5 g
C.
14.625 g
D.
0.5 g
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Solution
Mass of solute = moles × molar mass = 1 mol × 58.5 g/mol = 58.5 g. For 0.5 L, it is 0.5 mol × 58.5 g/mol = 29.25 g.
Correct Answer: A — 29.25 g
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Q. How many grams of solute are needed to prepare 2 L of a 1 M solution? (Molar mass = 58.5 g/mol)
A.
58.5 g
B.
117 g
C.
29.25 g
D.
145 g
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Solution
Grams of solute = moles x molar mass = 2 moles x 58.5 g/mol = 117 g.
Correct Answer: B — 117 g
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Q. How many molecules are present in 2 moles of water (H2O)?
A.
6.022 x 10^23
B.
1.2044 x 10^24
C.
3.011 x 10^23
D.
12.044 x 10^24
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Solution
Number of molecules = moles x Avogadro's number = 2 moles x 6.022 x 10^23 molecules/mole = 1.2044 x 10^24 molecules.
Correct Answer: B — 1.2044 x 10^24
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Q. How many moles are in 1.5 kg of KCl?
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Solution
Molar mass of KCl = 39 + 35.5 = 74.5 g/mol. Number of moles = mass/molar mass = 1500 g / 74.5 g/mol ≈ 20.1 moles.
Correct Answer: B — 20
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Q. How many moles are in 10 grams of NaOH?
A.
0.25
B.
0.5
C.
0.75
D.
1
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Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 10 g / 40 g/mol = 0.25 moles.
Correct Answer: A — 0.25
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Q. How many moles are in 100 grams of CaCO3?
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Solution
Molar mass of CaCO3 = 40 + 12 + 3*16 = 100 g/mol. Number of moles = mass/molar mass = 100 g / 100 g/mol = 1 mole.
Correct Answer: A — 1
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Q. How many moles are in 180 grams of water?
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Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = 180 g / 18 g/mol = 10 moles.
Correct Answer: A — 1
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Q. How many moles are in 200 grams of H2SO4?
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Solution
Molar mass of H2SO4 = 2 + 32 + 16*4 = 98 g/mol. Number of moles = 200 g / 98 g/mol = 2.04 moles.
Correct Answer: B — 2
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Q. How many moles are in 36 grams of water (H2O)?
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Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 36 g / 18 g/mol = 2 moles.
Correct Answer: A — 1
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