Basic Concepts of Chemistry
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
Show solution
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
Learn More →
Q. How many grams are in 0.25 moles of glucose (C6H12O6)?
A.
30 g
B.
45 g
C.
75 g
D.
90 g
Show solution
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
Learn More →
Q. How many grams are in 0.25 moles of KCl?
A.
35 g
B.
70 g
C.
17.5 g
D.
140 g
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
Q. How many grams are in 2 moles of carbon dioxide (CO2)?
A.
44 g
B.
88 g
C.
22 g
D.
66 g
Show solution
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
Learn More →
Q. How many grams are in 3 moles of glucose (C6H12O6)?
A.
180 g
B.
360 g
C.
540 g
D.
90 g
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
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
Show solution
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
Learn More →
Q. How many moles are in 1.5 kg of KCl?
Show solution
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
Learn More →
Q. How many moles are in 10 grams of NaOH?
A.
0.25
B.
0.5
C.
0.75
D.
1
Show solution
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
Learn More →
Q. How many moles are in 100 grams of CaCO3?
Show solution
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
Learn More →
Q. How many moles are in 180 grams of water?
Show solution
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
Learn More →
Q. How many moles are in 200 grams of H2SO4?
Show solution
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
Learn More →
Q. How many moles are in 36 grams of water (H2O)?
Show solution
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
Learn More →
Q. How many moles are in 5.6 liters of a gas at STP?
Show solution
Solution
At STP, 1 mole of gas occupies 22.4 L. Number of moles = volume / molar volume = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: C — 1
Learn More →
Q. How many moles are in 5.6 liters of an ideal gas at STP?
Show solution
Solution
At STP, 1 mole of gas occupies 22.4 L. Therefore, number of moles = 5.6 L / 22.4 L/mole = 0.25 moles.
Correct Answer: B — 0.5
Learn More →
Q. How many moles are in 50 grams of CaCO3?
Show solution
Solution
Molar mass of CaCO3 = 100 g/mol. Number of moles = mass / molar mass = 50 g / 100 g/mol = 0.5 moles.
Correct Answer: B — 1
Learn More →
Q. How many moles are in 50 grams of H2O?
A.
2.78
B.
1.39
C.
0.56
D.
3.06
Show solution
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = mass/molar mass = 50 g / 18 g/mol = 2.78 moles.
Correct Answer: B — 1.39
Learn More →
Q. How many moles are in 50 grams of NaOH?
Show solution
Solution
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol. Number of moles = mass/molar mass = 50 g / 40 g/mol = 1.25 moles.
Correct Answer: B — 0.5
Learn More →
Q. How many moles are in 50 grams of sodium (Na)?
A.
1.08
B.
2.5
C.
0.5
D.
0.25
Show solution
Solution
Molar mass of Na = 23 g/mol. Number of moles = mass / molar mass = 50 g / 23 g/mol ≈ 2.17 moles.
Correct Answer: A — 1.08
Learn More →
Q. How many moles are in 500 mL of a 2 M NaCl solution?
Show solution
Solution
Moles = molarity x volume (in L) = 2 M x 0.5 L = 1 mole.
Correct Answer: B — 1
Learn More →
Q. How many moles are in 88 grams of CH4?
Show solution
Solution
Molar mass of CH4 = 12 + 4*1 = 16 g/mol. Number of moles = mass/molar mass = 88 g / 16 g/mol = 5.5 moles.
Correct Answer: B — 2
Learn More →
Showing 1 to 30 of 153 (6 Pages)
