Q. For the equilibrium reaction: H2(g) + I2(g) ⇌ 2HI(g), what is the effect of adding more I2?
A.Equilibrium shifts to the right
B.Equilibrium shifts to the left
C.No effect
D.Equilibrium constant changes
Solution
Adding more I2 increases its concentration, which shifts the equilibrium to the right to produce more HI.
Correct Answer: A — Equilibrium shifts to the right
Q. For the equilibrium reaction: H2(g) + I2(g) ⇌ 2HI(g), what is the effect of adding more HI?
A.Shifts to the right
B.Shifts to the left
C.No change
D.Increases the rate of reaction
Solution
Adding more HI increases the concentration of products, which shifts the equilibrium to the left to form more reactants.
Correct Answer: B — Shifts to the left
Q. For the reaction 4HCl(g) ⇌ 2H2(g) + Cl2(g), what is the effect of adding HCl on the equilibrium?
A.Shift to the left
B.Shift to the right
C.No effect
D.Depends on the temperature
Solution
Adding more HCl will increase the concentration of reactants, causing the equilibrium to shift to the left to consume the added HCl.
Correct Answer: A — Shift to the left
Q. For the reaction A(g) ⇌ B(g), if the concentration of A is increased, what will happen to the concentration of B at equilibrium?
A.Increase
B.Decrease
C.Remain the same
D.Cannot be determined
Solution
Increasing the concentration of A will shift the equilibrium to the right, resulting in an increase in the concentration of B.
Correct Answer: A — Increase
Q. For the reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what is the effect of increasing the concentration of H2?
A.Shifts equilibrium to the right
B.Shifts equilibrium to the left
C.No effect
D.Increases the rate of reaction
Solution
Increasing the concentration of H2 will shift the equilibrium to the right to produce more CH3OH, according to Le Chatelier's principle.
Correct Answer: A — Shifts equilibrium to the right
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the concentration of NH3 is increased, what will happen to the equilibrium?
A.Shift to the right
B.Shift to the left
C.No change
D.Increase the rate of reaction
Solution
According to Le Chatelier's principle, increasing the concentration of a product (NH3) will shift the equilibrium to the left to counteract the change.
Correct Answer: B — Shift to the left
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens if the volume of the container is decreased?
A.Equilibrium shifts to the left
B.Equilibrium shifts to the right
C.No change in equilibrium
D.Equilibrium constant changes
Solution
Decreasing the volume increases the pressure, and according to Le Chatelier's principle, the equilibrium will shift towards the side with fewer moles of gas, which is the right side in this case.
Correct Answer: B — Equilibrium shifts to the right
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens to the equilibrium constant if the temperature is increased?
A.Increases
B.Decreases
C.Remains the same
D.Depends on the pressure
Solution
For exothermic reactions, increasing the temperature shifts the equilibrium to the left, thus decreasing the equilibrium constant.
Correct Answer: B — Decreases
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens to the equilibrium position if the pressure is increased?
A.Shifts to the left
B.Shifts to the right
C.No change
D.Depends on temperature
Solution
Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas. In this case, the right side has 2 moles of NH3 compared to 4 moles of reactants.
Correct Answer: B — Shifts to the right
Q. For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), what happens to the equilibrium position if the volume of the container is decreased?
A.Equilibrium shifts to the left
B.Equilibrium shifts to the right
C.No change in equilibrium
D.Equilibrium shifts in both directions
Solution
According to Le Chatelier's principle, decreasing the volume increases the pressure, and the equilibrium will shift towards the side with fewer moles of gas, which is the right side (2 moles of NH3).
Correct Answer: B — Equilibrium shifts to the right
Q. For the reaction: 3A(g) ⇌ 2B(g) + C(g), what is the expression for Kp?
A.(P_B^2 * P_C) / (P_A^3)
B.(P_A^3) / (P_B^2 * P_C)
C.(P_C) / (P_A^3)
D.(P_B^2) / (P_A^3)
Solution
The equilibrium constant Kp is expressed as Kp = (P_B^2 * P_C) / (P_A^3).
Correct Answer: A — (P_B^2 * P_C) / (P_A^3)
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
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
Q. For which of the following molecules is the molecular orbital diagram similar to that of O2?
A.N2
B.F2
C.C2
D.Ne2
Solution
The molecular orbital diagram of F2 is similar to that of O2, with the same energy level arrangement.
Correct Answer: B — F2
Q. How does the presence of a +M group affect the stability of a carbocation?
A.Increases stability
B.Decreases stability
C.No effect
D.Depends on the solvent
Solution
A +M group increases the stability of a carbocation by donating electron density through resonance.
Correct Answer: A — Increases stability
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
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
Q. How many grams are in 0.25 moles of glucose (C6H12O6)?
A.30 g
B.45 g
C.75 g
D.90 g
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
Q. How many grams are in 0.25 moles of KCl?
A.35 g
B.70 g
C.17.5 g
D.140 g
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
Q. How many grams are in 2 moles of carbon dioxide (CO2)?
A.44 g
B.88 g
C.22 g
D.66 g
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
Q. How many grams are in 3 moles of glucose (C6H12O6)?
A.180 g
B.360 g
C.540 g
D.90 g
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Solution
Grams of solute = moles x molar mass = 2 moles x 58.5 g/mol = 117 g.
Correct Answer: B — 117 g
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
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
Q. How many moles are in 10 grams of NaOH?
A.0.25
B.0.5
C.0.75
D.1
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
Q. How many moles are in 100 grams of CaCO3?
A.1
B.2
C.0.5
D.0.25
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
Q. How many moles are in 180 grams of water?
A.1
B.2
C.3
D.4
Solution
Molar mass of H2O = 2*1 + 16 = 18 g/mol. Number of moles = 180 g / 18 g/mol = 10 moles.
