Physical Chemistry
Q. If the equilibrium constant Kc for a reaction is 10, what can be said about the position of equilibrium?
A.
Products are favored
B.
Reactants are favored
C.
Equilibrium is at the center
D.
No conclusion can be drawn
Show solution
Solution
A Kc value greater than 1 indicates that the products are favored at equilibrium.
Correct Answer: A — Products are favored
Learn More →
Q. If the forward reaction is exothermic, what effect does increasing the temperature have on the equilibrium position?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the rate of reaction
Show solution
Solution
According to Le Chatelier's principle, increasing the temperature of an exothermic reaction shifts the equilibrium position to the left, favoring the reactants.
Correct Answer: B — Shifts to the left
Learn More →
Q. If the mole fraction of a solute in a solution is 0.2, what is the mole fraction of the solvent?
A.
0.8
B.
0.2
C.
0.5
D.
0.6
Show solution
Solution
Mole fraction of solvent = 1 - mole fraction of solute = 1 - 0.2 = 0.8.
Correct Answer: A — 0.8
Learn More →
Q. If the mole fraction of a solvent in a solution is 0.75, what is the vapor pressure of the solvent if its pure vapor pressure is 100 mmHg?
A.
75 mmHg
B.
100 mmHg
C.
25 mmHg
D.
50 mmHg
Show solution
Solution
According to Raoult's Law, the vapor pressure of the solvent in the solution is 0.75 * 100 mmHg = 75 mmHg.
Correct Answer: A — 75 mmHg
Learn More →
Q. If the mole fraction of solute in a solution is 0.2, what is the mole fraction of the solvent?
A.
0.8
B.
0.2
C.
0.5
D.
0.6
Show solution
Solution
The mole fraction of the solvent is 1 - X_solute = 1 - 0.2 = 0.8.
Correct Answer: A — 0.8
Learn More →
Q. If the osmotic pressure of a solution is 3.0 atm at 25 °C, what is the molarity of the solution? (R = 0.0821 L atm/(K mol))
A.
0.12 M
B.
0.15 M
C.
0.18 M
D.
0.20 M
Show solution
Solution
Molarity = π / (RT) = 3.0 / (0.0821 * 298) = 0.12 M
Correct Answer: C — 0.18 M
Learn More →
Q. If the osmotic pressure of a solution is 3.0 atm, what is the molarity of the solution? (R = 0.0821 L atm/(K mol), T = 298 K)
A.
0.12 M
B.
0.15 M
C.
0.10 M
D.
0.20 M
Show solution
Solution
Molarity = π / (RT) = 3.0 / (0.0821 * 298) = 0.12 M
Correct Answer: B — 0.15 M
Learn More →
Q. If the principal quantum number n = 4 and the azimuthal quantum number l = 2, what is the maximum number of electrons in this subshell?
Show solution
Solution
The maximum number of electrons in a subshell is given by 2(2l + 1). For l = 2, it is 2(2*2 + 1) = 10.
Correct Answer: C — 14
Learn More →
Q. If the principal quantum number n = 4, what are the possible values of l?
A.
0, 1, 2, 3
B.
1, 2, 3, 4
C.
0, 1, 2, 3, 4
D.
0, 1, 2
Show solution
Solution
For n=4, l can take values 0, 1, 2, or 3.
Correct Answer: A — 0, 1, 2, 3
Learn More →
Q. If the principal quantum number n = 4, what are the possible values of the azimuthal quantum number l?
A.
0, 1, 2, 3
B.
1, 2, 3, 4
C.
0, 1, 2, 3, 4
D.
0, 1, 2
Show solution
Solution
For n=4, l can take values from 0 to n-1, which are 0, 1, 2, and 3.
Correct Answer: A — 0, 1, 2, 3
Learn More →
Q. If the quadratic equation x^2 + kx + 9 = 0 has no real roots, what is the condition on k?
A.
k < 6
B.
k > 6
C.
k < 0
D.
k > 0
Show solution
Solution
The discriminant must be less than zero: k^2 - 4*1*9 < 0 => k^2 < 36 => |k| < 6.
Correct Answer: B — k > 6
Learn More →
Q. If the rate of a reaction doubles when the temperature is increased by 10°C, what is the approximate activation energy (Ea) of the reaction?
A.
20 kJ/mol
B.
40 kJ/mol
C.
60 kJ/mol
D.
80 kJ/mol
Show solution
Solution
Using the Arrhenius equation, a rule of thumb states that for every 10°C increase in temperature, the rate doubles if Ea is around 40 kJ/mol.
Correct Answer: B — 40 kJ/mol
Learn More →
Q. If the roots of the equation x^2 + 3x + k = 0 are real and distinct, what is the range of k?
A.
k < 9
B.
k > 9
C.
k < 0
D.
k > 0
Show solution
Solution
For real and distinct roots, the discriminant must be positive: 3^2 - 4*1*k > 0 => 9 - 4k > 0 => k < 9.
Correct Answer: A — k < 9
Learn More →
Q. If the roots of the equation x^2 + 5x + k = 0 are -2 and -3, find k.
Show solution
Solution
Using Vieta's formulas, k = (-2)(-3) = 6.
Correct Answer: B — 6
Learn More →
Q. If the roots of the equation x^2 - 6x + k = 0 are 2 and 4, find the value of k.
Show solution
Solution
Using Vieta's formulas, k = 2 * 4 = 8.
Correct Answer: B — 10
Learn More →
Q. If the solubility product (Ksp) of AgCl is 1.77 x 10^-10, what is the molar solubility of AgCl?
A.
1.77 x 10^-5 M
B.
1.77 x 10^-10 M
C.
1.77 x 10^-7 M
D.
1.77 x 10^-3 M
Show solution
Solution
Ksp = [Ag+][Cl-] = s^2, thus s = sqrt(1.77 x 10^-10) = 1.77 x 10^-5 M.
Correct Answer: C — 1.77 x 10^-7 M
Learn More →
Q. If the temperature of a gas is doubled at constant pressure, what happens to its volume?
A.
It halves
B.
It doubles
C.
It remains the same
D.
It quadruples
Show solution
Solution
According to Charles's Law, at constant pressure, the volume of a gas is directly proportional to its temperature.
Correct Answer: B — It doubles
Learn More →
Q. If the temperature of a system is increased, what happens to its entropy?
A.
It decreases
B.
It remains constant
C.
It increases
D.
It becomes zero
Show solution
Solution
As the temperature of a system increases, the kinetic energy of the particles increases, leading to greater disorder and thus an increase in entropy.
Correct Answer: C — It increases
Learn More →
Q. If the vapor pressure of a pure solvent is 80 mmHg and a non-volatile solute is added, resulting in a vapor pressure of 60 mmHg, what is the mole fraction of the solvent in the solution?
A.
0.75
B.
0.50
C.
0.25
D.
0.80
Show solution
Solution
Using Raoult's Law, P_solution = X_solvent * P_pure_solvent; 60 mmHg = X_solvent * 80 mmHg; X_solvent = 60/80 = 0.75.
Correct Answer: A — 0.75
Learn More →
Q. If the vapor pressure of a solution is 80 mmHg and the vapor pressure of the pure solvent is 120 mmHg, what is the mole fraction of the solvent in the solution?
A.
0.67
B.
0.33
C.
0.50
D.
0.75
Show solution
Solution
Using Raoult's Law, P_solution = X_solvent * P_solvent^0; 80 = X_solvent * 120; X_solvent = 80/120 = 0.67.
Correct Answer: A — 0.67
Learn More →
Q. If the vapor pressure of pure solvent A is 100 mmHg, and the mole fraction of A in the solution is 0.6, what is the vapor pressure of the solution according to Raoult's Law?
A.
60 mmHg
B.
100 mmHg
C.
40 mmHg
D.
80 mmHg
Show solution
Solution
Using Raoult's Law, P_solution = X_A * P_A^0 = 0.6 * 100 mmHg = 60 mmHg.
Correct Answer: A — 60 mmHg
Learn More →
Q. If the vapor pressure of pure solvent A is 100 mmHg, what is the vapor pressure of a solution containing 0.5 mole fraction of A?
A.
50 mmHg
B.
100 mmHg
C.
75 mmHg
D.
25 mmHg
Show solution
Solution
According to Raoult's Law, the vapor pressure of the solution is 0.5 * 100 mmHg = 50 mmHg.
Correct Answer: A — 50 mmHg
Learn More →
Q. If the vapor pressure of pure solvent is 120 mmHg, what will be the vapor pressure of a solution containing 0.2 moles of solute in 1 mole of solvent?
A.
100 mmHg
B.
110 mmHg
C.
120 mmHg
D.
80 mmHg
Show solution
Solution
Using Raoult's Law, the vapor pressure of the solution is P_solution = P_solvent * X_solvent = 120 * (1/(1+0.2)) = 120 * (1/1.2) = 100 mmHg.
Correct Answer: B — 110 mmHg
Learn More →
Q. If x + 4 = 10, what is the value of x?
Show solution
Solution
Subtracting 4 from both sides gives x = 6.
Correct Answer: B — 6
Learn More →
Q. If ΔG is negative for a reaction, what can be inferred about the reaction?
A.
The reaction is at equilibrium.
B.
The reaction is spontaneous.
C.
The reaction is non-spontaneous.
D.
The reaction requires energy input.
Show solution
Solution
A negative ΔG indicates that the reaction is spontaneous.
Correct Answer: B — The reaction is spontaneous.
Learn More →
Q. If ΔG is negative for a reaction, what can be inferred?
A.
The reaction is non-spontaneous.
B.
The reaction is at equilibrium.
C.
The reaction is spontaneous.
D.
The reaction requires energy input.
Show solution
Solution
A negative ΔG indicates that the reaction is spontaneous under the given conditions.
Correct Answer: C — The reaction is spontaneous.
Learn More →
Q. If ΔG is negative, what does it indicate about the reaction?
A.
Reaction is at equilibrium
B.
Reaction is spontaneous
C.
Reaction is non-spontaneous
D.
Reaction requires energy input
Show solution
Solution
A negative ΔG indicates that the reaction is spontaneous.
Correct Answer: B — Reaction is spontaneous
Learn More →
Q. If ΔG is positive, what can be inferred about the reaction?
A.
The reaction is spontaneous.
B.
The reaction is at equilibrium.
C.
The reaction is non-spontaneous.
D.
The reaction will proceed in reverse.
Show solution
Solution
If ΔG is positive, the reaction is non-spontaneous under the given conditions.
Correct Answer: C — The reaction is non-spontaneous.
Learn More →
Q. If ΔH = 100 kJ and ΔS = 0.2 kJ/K, what is ΔG at 298 K?
A.
100 kJ
B.
96 kJ
C.
104 kJ
D.
90 kJ
Show solution
Solution
ΔG = ΔH - TΔS = 100 kJ - 298 K * 0.2 kJ/K = 100 kJ - 59.6 kJ = 40.4 kJ.
Correct Answer: B — 96 kJ
Learn More →
Q. If ΔH is negative and ΔS is positive, what can be said about ΔG?
A.
ΔG is always positive.
B.
ΔG is always negative.
C.
ΔG can be positive or negative depending on temperature.
D.
ΔG is zero.
Show solution
Solution
If ΔH is negative and ΔS is positive, ΔG will always be negative, indicating that the reaction is spontaneous at all temperatures.
Correct Answer: B — ΔG is always negative.
Learn More →
Showing 211 to 240 of 1385 (47 Pages)
