JEE Main
Q. In which process does the entropy of the system decrease?
A.
Freezing of water
B.
Evaporation of water
C.
Sublimation of dry ice
D.
Dissolving salt in water
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Solution
The freezing of water results in a decrease in the entropy of the system as it transitions from liquid to solid.
Correct Answer: A — Freezing of water
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Q. In which scenario would the frictional force be at its maximum?
A.
When an object is at rest
B.
When an object is sliding
C.
When an object is rolling
D.
When an object is in free fall
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Solution
The maximum frictional force occurs when an object is at rest, just before it starts to slide, which is characterized by static friction.
Correct Answer: A — When an object is at rest
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Q. In which scenario would the Gibbs Free Energy of a system be at its minimum?
A.
At equilibrium
B.
At the start of a reaction
C.
At maximum temperature
D.
At maximum pressure
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Solution
The Gibbs Free Energy of a system is at its minimum at equilibrium, indicating stability.
Correct Answer: A — At equilibrium
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Q. In which scenario would total internal reflection NOT occur?
A.
Light traveling from glass to air at a steep angle.
B.
Light traveling from water to air at a shallow angle.
C.
Light traveling from diamond to air at a high angle.
D.
Light traveling from air to water at any angle.
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Solution
Total internal reflection cannot occur when light travels from a rarer medium (air) to a denser medium (water) at any angle, as it will always refract.
Correct Answer: D — Light traveling from air to water at any angle.
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Q. In which scenario would ΔG = 0?
A.
At the start of a reaction.
B.
At equilibrium.
C.
When the reaction is spontaneous.
D.
When the reaction is non-spontaneous.
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Solution
ΔG = 0 occurs at equilibrium, where the forward and reverse reactions occur at the same rate.
Correct Answer: B — At equilibrium.
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Q. In which scenario would ΔG be equal to ΔH?
A.
At absolute zero.
B.
When ΔS = 0.
C.
For a spontaneous reaction.
D.
For an endothermic reaction.
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Solution
ΔG equals ΔH when the entropy change (ΔS) is zero, indicating no change in disorder.
Correct Answer: B — When ΔS = 0.
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Q. In which scenario would ΔG be zero?
A.
At standard conditions
B.
At equilibrium
C.
In a spontaneous reaction
D.
In a non-spontaneous reaction
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Solution
ΔG is zero at equilibrium, indicating no net change in the concentrations of reactants and products.
Correct Answer: B — At equilibrium
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Q. In which state of matter do particles have the highest kinetic energy?
A.
Solid
B.
Liquid
C.
Gas
D.
Plasma
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Solution
Plasma has the highest kinetic energy as the particles are highly energized and ionized.
Correct Answer: D — Plasma
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Q. In which type of reaction is the change in enthalpy equal to the heat absorbed or released at constant pressure?
A.
Endothermic reaction
B.
Exothermic reaction
C.
Isothermal reaction
D.
Adiabatic reaction
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Solution
In an endothermic reaction, the change in enthalpy is equal to the heat absorbed at constant pressure.
Correct Answer: A — Endothermic reaction
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Q. In Young's double-slit experiment, if the distance between the slits is 0.2 mm and the distance to the screen is 1 m, what is the fringe width if the wavelength of light used is 500 nm?
A.
0.1 mm
B.
0.2 mm
C.
0.5 mm
D.
0.8 mm
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Solution
Fringe width (β) = λD/d. Here, D = 1 m, d = 0.2 mm = 0.0002 m, λ = 500 nm = 500 x 10^-9 m. β = (500 x 10^-9 * 1) / 0.0002 = 0.0025 m = 0.25 mm.
Correct Answer: A — 0.1 mm
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Q. In Young's double-slit experiment, if the distance between the slits is 0.2 mm and the distance from the slits to the screen is 1 m, what is the distance between the first and second bright fringes?
A.
0.1 mm
B.
0.2 mm
C.
0.4 mm
D.
0.6 mm
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Solution
Distance between fringes (y) = (λD)/d. Assuming λ = 500 nm, y = (500 x 10^-9 * 1)/(0.2 x 10^-3) = 0.0025 m = 0.25 mm. Distance between first and second bright fringes = 0.4 mm.
Correct Answer: C — 0.4 mm
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Q. In Young's double-slit experiment, if the distance between the slits is doubled while keeping the wavelength constant, what happens to the fringe width?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Fringe width (β) is given by β = λD/d, where D is the distance to the screen and d is the distance between the slits. If d is doubled, β halves.
Correct Answer: B — It halves
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Q. In Young's double-slit experiment, if the distance between the slits is doubled, what happens to the fringe width?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Fringe width is given by β = λD/d. If d (distance between slits) is doubled, the fringe width β will halve.
Correct Answer: B — It halves
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Q. Is the function f(x) = x^2 - 2x + 1 differentiable at x = 1?
A.
Yes
B.
No
C.
Only from the left
D.
Only from the right
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Solution
f(x) is a polynomial function, which is differentiable everywhere, including at x = 1.
Correct Answer: A — Yes
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Q. Is the function f(x) = x^2 - 4x + 4 differentiable at x = 2?
A.
Yes
B.
No
C.
Only from the left
D.
Only from the right
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Solution
The function is a polynomial and is differentiable everywhere, hence yes.
Correct Answer: A — Yes
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Q. Is the function f(x) = x^2 sin(1/x) differentiable at x = 0?
A.
Yes
B.
No
C.
Only from the left
D.
Only from the right
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Solution
Using the limit definition, f'(0) = lim (h -> 0) [(h^2 sin(1/h) - 0)/h] = 0. Thus, f(x) is differentiable at x = 0.
Correct Answer: A — Yes
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Q. Is the function f(x) = x^3 - 3x + 2 differentiable at x = 1?
A.
Yes
B.
No
C.
Only left differentiable
D.
Only right differentiable
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Solution
The function is a polynomial and hence differentiable everywhere, including at x = 1.
Correct Answer: A — Yes
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Q. Is the function f(x) = { e^x, x < 0; ln(x + 1), x >= 0 } continuous at x = 0?
A.
Yes
B.
No
C.
Only left continuous
D.
Only right continuous
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Solution
Both limits as x approaches 0 from the left and right are equal to 1, hence f(x) is continuous at x = 0.
Correct Answer: A — Yes
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Q. Is the function f(x) = { sin(x), x < 0; x^2, x >= 0 } continuous at x = 0?
A.
Yes
B.
No
C.
Depends on x
D.
Not defined
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Solution
Both limits as x approaches 0 from the left and right are equal to 0, hence f(x) is continuous at x = 0.
Correct Answer: A — Yes
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Q. Is the function f(x) = { x^3, x < 1; 2x + 1, x >= 1 } continuous at x = 1?
A.
Yes
B.
No
C.
Only left continuous
D.
Only right continuous
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Solution
Both limits as x approaches 1 from the left and right are equal to 2, hence f(x) is continuous at x = 1.
Correct Answer: A — Yes
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Q. Is the function f(x) = |x|/x continuous at x = 0?
A.
Yes
B.
No
C.
Depends on direction
D.
None of the above
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Solution
The left limit is -1 and the right limit is 1, which are not equal. Therefore, f(x) is not continuous at x = 0.
Correct Answer: B — No
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Q. Lenz's law states that the direction of induced current is such that it opposes what?
A.
The change in magnetic flux
B.
The flow of electric current
C.
The resistance in the circuit
D.
The applied voltage
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Solution
Lenz's law states that the direction of induced current will oppose the change in magnetic flux that produced it.
Correct Answer: A — The change in magnetic flux
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Q. Let A = {1, 2, 3, 4} and R be the relation defined by R = {(a, b) | a < b}. How many ordered pairs are in R?
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Solution
The pairs are (1,2), (1,3), (1,4), (2,3), (2,4), (3,4). Thus, there are 6 ordered pairs.
Correct Answer: B — 6
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Q. Let A = {1, 2, 3, 4} and R be the relation defined by R = {(x, y) | x < y}. How many ordered pairs are in R?
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Solution
The ordered pairs are (1,2), (1,3), (1,4), (2,3), (2,4), (3,4). Thus, there are 6 ordered pairs.
Correct Answer: B — 6
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Q. Let R be a relation on the set of natural numbers defined by R = {(m, n) | m divides n}. Is R a partial order?
A.
Yes
B.
No
C.
Only reflexive
D.
Only transitive
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Solution
R is reflexive, antisymmetric, and transitive, thus it is a partial order.
Correct Answer: A — Yes
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Q. Solve for x: 2x^2 - 8x + 6 = 0.
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Solution
Using the quadratic formula x = [8 ± √(64 - 48)] / 4 = [8 ± 4] / 4, giving x = 3 or x = 1.
Correct Answer: B — 3
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Q. Solve for x: 3(x - 1) = 2(x + 4).
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Solution
Expanding gives 3x - 3 = 2x + 8. Rearranging gives x = 11.
Correct Answer: A — -10
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Q. Solve for x: 3(x - 2) = 12.
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Solution
Dividing both sides by 3 gives x - 2 = 4, thus x = 6.
Correct Answer: C — 6
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Q. Solve for x: 3(x - 2) = 2(x + 1).
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Solution
Expanding both sides gives 3x - 6 = 2x + 2. Rearranging gives x = 8.
Correct Answer: B — 0
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Q. Solve for x: 5x + 2 = 3x + 10.
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Solution
Subtracting 3x from both sides gives 2x + 2 = 10, then subtracting 2 gives 2x = 8, leading to x = 4.
Correct Answer: A — 4
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