Q. If the equation x^2 - 5x + k = 0 has equal roots, what is the value of k?
Show solution
Solution
For equal roots, the discriminant must be zero. Thus, (-5)^2 - 4*1*k = 0 => 25 - 4k = 0 => k = 25/4 = 6.25.
Correct Answer: A — 5
Learn More →
Q. If the equilibrium constant Kc for a reaction is 10 at a certain temperature, what is the value of Kc for the reverse reaction?
Show solution
Solution
The equilibrium constant for the reverse reaction is the reciprocal of the forward reaction, so Kc' = 1/Kc = 0.1.
Correct Answer: A — 0.1
Learn More →
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 equilibrium constant Kc for a reaction is less than 1, what does it indicate about the equilibrium position?
A.
Products are favored
B.
Reactants are favored
C.
Equal amounts of reactants and products
D.
Reaction does not occur
Show solution
Solution
A Kc value less than 1 indicates that at equilibrium, the concentration of reactants is greater than that of products, thus reactants are favored.
Correct Answer: B — Reactants 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 a solvent in a solution is 0.8, what is the mole fraction of the solute?
A.
0.2
B.
0.8
C.
0.5
D.
0.1
Show solution
Solution
The mole fraction of the solute is 1 - X_solvent = 1 - 0.8 = 0.2.
Correct Answer: A — 0.2
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, and the mole fraction of A in the solution is 0.5, what is the vapor pressure of the solution according to Raoult's Law?
A.
50 mmHg
B.
100 mmHg
C.
150 mmHg
D.
200 mmHg
Show solution
Solution
According to Raoult's Law, P_solution = X_A * P_A^0 = 0.5 * 100 mmHg = 50 mmHg.
Correct Answer: A — 50 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 the vapor pressure of pure solvent is 80 mmHg and the mole fraction of the solvent in the solution is 0.75, what is the vapor pressure of the solution?
A.
60 mmHg
B.
80 mmHg
C.
75 mmHg
D.
20 mmHg
Show solution
Solution
Using Raoult's Law, P_solution = X_solvent * P_solvent^0 = 0.75 * 80 mmHg = 60 mmHg.
Correct Answer: A — 60 mmHg
Learn More →
Q. If the vapor pressure of pure water is 23.8 mmHg at 25°C, what is the vapor pressure of a solution containing 1 mole of NaCl in 1 kg of water?
A.
20.0 mmHg
B.
22.0 mmHg
C.
23.0 mmHg
D.
23.8 mmHg
Show solution
Solution
Using Raoult's law, the vapor pressure lowering is calculated considering the van 't Hoff factor for NaCl.
Correct Answer: B — 22.0 mmHg
Learn More →
Showing 241 to 270 of 2802 (94 Pages)