Major Competitive Exams
Q. What is the value of x where f(x) = x^3 - 3x has a local maximum? (2022)
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Solution
f'(x) = 3x^2 - 3. Setting f'(x) = 0 gives x = ±1. f(1) = -2.
Correct Answer: C — 1
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Q. What is the value of z if z^2 = -1?
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Solution
The solutions to z^2 = -1 are z = i and z = -i.
Correct Answer: A — i
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Q. What is the value of \( \begin{vmatrix} 1 & 1 & 1 \\ 1 & 2 & 3 \\ 1 & 3 & 6 \end{vmatrix} \)?
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Solution
The determinant is 0 because the first column is repeated.
Correct Answer: A — 0
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Q. What is the value of \( \tan(\tan^{-1}(3)) \)?
A.
0
B.
1
C.
3
D.
undefined
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Solution
By definition, \( \tan(\tan^{-1}(x)) = x \). Therefore, \( \tan(\tan^{-1}(3)) = 3 \).
Correct Answer: C — 3
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Q. What is the value of \( |D| \) for the matrix \( D = \begin{pmatrix} 0 & 1 \\ 1 & 0 \end{pmatrix} \)? (2023)
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Solution
The determinant is \( 0*0 - 1*1 = 0 - 1 = -1 \).
Correct Answer: A — 1
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Q. What is the value of |z| if z = -3 + 4i?
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Solution
|z| = √((-3)^2 + (4)^2) = √(9 + 16) = √25 = 5.
Correct Answer: A — 5
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Q. What is the value of |z| if z = 4 - 3i?
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Solution
|z| = √(4^2 + (-3)^2) = √(16 + 9) = √25 = 5.
Correct Answer: A — 5
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Q. What is the value of |z| if z = 4e^(iπ/3)?
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Solution
The modulus |z| = 4, as it is the coefficient in the polar form.
Correct Answer: A — 4
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Q. What is the value of |z|^2 if z = 4 - 3i?
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Solution
|z|^2 = 4^2 + (-3)^2 = 16 + 9 = 25.
Correct Answer: A — 25
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Q. What is the van 't Hoff factor (i) for a strong electrolyte like Na2SO4 in solution? (2023)
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Solution
Na2SO4 dissociates into 3 ions (2 Na⁺ and 1 SO4²⁻), so i = 3.
Correct Answer: C — 3
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Q. What is the van 't Hoff factor (i) for a strong electrolyte like NaCl in solution?
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Solution
NaCl dissociates into two ions (Na+ and Cl-), so the van 't Hoff factor (i) is 2.
Correct Answer: B — 2
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Q. What is the van 't Hoff factor (i) for a strong electrolyte that completely dissociates into 3 ions?
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Solution
The van 't Hoff factor (i) is equal to the number of particles the solute dissociates into. For a strong electrolyte that dissociates into 3 ions, i = 3.
Correct Answer: C — 3
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Q. What is the van 't Hoff factor (i) for glucose in solution?
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Solution
The van 't Hoff factor (i) for glucose is 1, as it does not dissociate in solution.
Correct Answer: A — 1
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Q. What is the van 't Hoff factor for a non-electrolyte solute?
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Solution
For a non-electrolyte solute, the van 't Hoff factor (i) is 1, as it does not dissociate into ions.
Correct Answer: B — 1
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Q. What is the vapor pressure of a solution containing 0.1 mol of a non-volatile solute in 1 kg of water? (Vapor pressure of pure water = 23.76 mmHg)
A.
22.88 mmHg
B.
21.76 mmHg
C.
20.76 mmHg
D.
19.76 mmHg
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Solution
Vapor pressure = P°_solvent * (n_solvent / (n_solvent + n_solute)) = 23.76 * (55.5 / (55.5 + 0.1)) = 22.88 mmHg
Correct Answer: A — 22.88 mmHg
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Q. What is the vapor pressure of a solution containing 1 mole of a non-volatile solute in 9 moles of solvent, if the vapor pressure of the pure solvent is 100 mmHg?
A.
90 mmHg
B.
100 mmHg
C.
10 mmHg
D.
80 mmHg
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Solution
Using Raoult's law, P_solution = X_solvent * P°_solvent = (9/10) * 100 mmHg = 90 mmHg.
Correct Answer: A — 90 mmHg
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Q. What is the vapor pressure of a solution containing 1 mole of a non-volatile solute in 3 moles of solvent, assuming ideal behavior?
A.
0.25 P0
B.
0.75 P0
C.
1.0 P0
D.
0.5 P0
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Solution
Vapor pressure lowering = (moles of solute / total moles) * P0 = (1 / (1 + 3)) * P0 = 0.25 P0, so vapor pressure = P0 - 0.25 P0 = 0.75 P0.
Correct Answer: B — 0.75 P0
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Q. What is the vapor pressure of a solution containing 1 mole of a non-volatile solute in 10 moles of solvent, assuming ideal behavior?
A.
0.1 P0
B.
0.9 P0
C.
1.0 P0
D.
0.5 P0
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Solution
Using Raoult's law, the vapor pressure of the solution = (moles of solvent / total moles) * P0 = (10 / 11) * P0 = 0.909 P0.
Correct Answer: B — 0.9 P0
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Q. What is the vapor pressure of a solution containing 1 mole of non-volatile solute in 3 moles of solvent if the vapor pressure of the pure solvent is 100 mmHg?
A.
75 mmHg
B.
100 mmHg
C.
25 mmHg
D.
50 mmHg
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Solution
Using Raoult's law, P_solution = X_solvent * P°_solvent. X_solvent = 3/(1+3) = 0.75, so P_solution = 0.75 * 100 mmHg = 75 mmHg.
Correct Answer: A — 75 mmHg
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Q. What is the vapor pressure of a solution containing 1 mole of solute in 3 moles of solvent, assuming ideal behavior?
A.
0.25 P0
B.
0.75 P0
C.
0.5 P0
D.
P0
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Solution
Using Raoult's law, the vapor pressure of the solution = (moles of solvent / total moles) * P0 = (3 / (3 + 1)) * P0 = 0.75 P0.
Correct Answer: B — 0.75 P0
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Q. What is the vapor pressure of a solution containing 1 mole of solute in 9 moles of solvent, assuming ideal behavior? (2019)
A.
0.1 P0
B.
0.9 P0
C.
0.5 P0
D.
0.2 P0
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Solution
Using Raoult's law, the vapor pressure of the solution = (moles of solvent / total moles) * P0 = (9 / 10) * P0 = 0.9 P0.
Correct Answer: B — 0.9 P0
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Q. What is the vapor pressure of a solution containing a non-volatile solute compared to the pure solvent?
A.
Higher than the pure solvent
B.
Lower than the pure solvent
C.
Equal to the pure solvent
D.
Unpredictable
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Solution
The vapor pressure of a solution containing a non-volatile solute is lower than that of the pure solvent due to the presence of solute particles.
Correct Answer: B — Lower than the pure solvent
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Q. What is the variance of the data set {4, 8, 6, 5, 3}?
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Solution
Mean = 5.2; Variance = [(4-5.2)² + (8-5.2)² + (6-5.2)² + (5-5.2)² + (3-5.2)²] / 5 = 2.56.
Correct Answer: A — 2.5
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Q. What is the variance of the data set: 1, 2, 3, 4, 5?
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Solution
Mean = 3. Variance = [(1-3)² + (2-3)² + (3-3)² + (4-3)² + (5-3)²] / 5 = 2.
Correct Answer: B — 1.5
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Q. What is the variance of the data set: 2, 4, 4, 4, 5, 5, 7, 9?
A.
2.5
B.
3.5
C.
4.5
D.
5.5
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Solution
Mean = 5.0; Variance = [(2-5)^2 + (4-5)^2 + (4-5)^2 + (4-5)^2 + (5-5)^2 + (5-5)^2 + (7-5)^2 + (9-5)^2] / 8 = 2.5.
Correct Answer: A — 2.5
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Q. What is the variance of the following data set: {5, 7, 8, 9, 10}?
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Solution
Mean = 7.8, Variance = [(5-7.8)² + (7-7.8)² + (8-7.8)² + (9-7.8)² + (10-7.8)²] / 5 = 3.
Correct Answer: B — 3
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Q. What is the vertex of the parabola defined by the equation y = -2(x - 1)^2 + 4?
A.
(1, 4)
B.
(1, -4)
C.
(4, 1)
D.
(-1, 4)
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Solution
The vertex form of a parabola is y = a(x - h)^2 + k. Here, h = 1 and k = 4, so the vertex is (1, 4).
Correct Answer: A — (1, 4)
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Q. What is the vertex of the parabola given by the equation y = -2(x - 1)^2 + 4?
A.
(1, 4)
B.
(1, -4)
C.
(4, 1)
D.
(-1, 4)
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Solution
The vertex form of a parabola is y = a(x - h)^2 + k. Here, h = 1 and k = 4, so the vertex is (1, 4).
Correct Answer: A — (1, 4)
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Q. What is the vertex of the parabola represented by the equation y = -2(x - 1)^2 + 4?
A.
(1, 4)
B.
(1, -4)
C.
(-1, 4)
D.
(-1, -4)
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Solution
The vertex form of a parabola is y = a(x - h)^2 + k. Here, h = 1 and k = 4, so the vertex is (1, 4).
Correct Answer: A — (1, 4)
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Q. What is the vertex of the parabola represented by the equation y = 2x^2 - 8x + 5?
A.
(2, -3)
B.
(2, -7)
C.
(4, -3)
D.
(4, -7)
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Solution
The vertex can be found using x = -b/(2a) = 4. Substituting x = 4 into the equation gives y = -3.
Correct Answer: A — (2, -3)
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