Major Competitive Exams
Q. If the latent heat of fusion of ice is 334 J/g, how much heat is required to melt 50 g of ice? (2019)
A.
1670 J
B.
3340 J
C.
5000 J
D.
1000 J
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Solution
Heat required = mass × latent heat = 50 g × 334 J/g = 16700 J.
Correct Answer: A — 1670 J
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Q. If the LCM of three numbers is 180 and their HCF is 3, what is the product of the three numbers? (2023)
A.
540
B.
1800
C.
5400
D.
18000
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Solution
The product of the three numbers is equal to LCM * HCF^2. Therefore, 180 * 3^2 = 180 * 9 = 1620.
Correct Answer: C — 5400
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Q. If the LCM of two numbers is 120 and their HCF is 10, what is the product of the two numbers? (2023)
A.
1200
B.
1000
C.
2400
D.
600
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Solution
The product of two numbers is equal to the product of their LCM and HCF. Therefore, 120 * 10 = 1200.
Correct Answer: A — 1200
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Q. If the LCM of two numbers is 60 and their HCF is 4, what is the product of the two numbers? (2023)
A.
240
B.
120
C.
300
D.
180
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Solution
The product of two numbers is equal to the product of their LCM and HCF. Therefore, 60 * 4 = 240.
Correct Answer: A — 240
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Q. If the least common multiple (LCM) of two numbers is 60 and their greatest common divisor (GCD) is 12, what is the product of the two numbers?
A.
720
B.
180
C.
120
D.
60
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Solution
The product of two numbers is equal to the product of their LCM and GCD. Therefore, 60 * 12 = 720.
Correct Answer: A — 720
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Q. If the length of a side of a cube is doubled, how does its volume change?
A.
Increases by 2 times
B.
Increases by 4 times
C.
Increases by 8 times
D.
Remains the same
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Solution
The volume of a cube is given by V = a³. If the side length a is doubled, the new volume is (2a)³ = 8a³, which is 8 times the original volume.
Correct Answer: C — Increases by 8 times
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Q. If the length of a side of a cube is doubled, how does the volume change?
A.
Increases by 2 times
B.
Increases by 4 times
C.
Increases by 8 times
D.
Remains the same
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Solution
Volume of a cube is given by V = a³. If a is doubled, V becomes (2a)³ = 8a³, hence volume increases by 8 times.
Correct Answer: C — Increases by 8 times
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Q. If the length of a side of a cube is measured as 2.0 ± 0.1 m, what is the maximum possible error in the volume of the cube?
A.
0.8 m³
B.
0.4 m³
C.
0.2 m³
D.
0.1 m³
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Solution
Volume V = L³. The maximum error in volume can be calculated using the formula: ΔV = 3L²ΔL. Here, ΔL = 0.1 m, L = 2.0 m, so ΔV = 3(2.0)²(0.1) = 1.2 m³.
Correct Answer: B — 0.4 m³
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Q. If the length of a side of a cube is measured as 2.5 cm with an uncertainty of 0.1 cm, what is the volume of the cube?
A.
15.625 cm³
B.
16.0 cm³
C.
16.5 cm³
D.
17.0 cm³
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Solution
Volume = side³ = (2.5 cm)³ = 15.625 cm³. Considering significant figures, it is reported as 16.0 cm³.
Correct Answer: B — 16.0 cm³
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Q. If the length of a side of a cube is measured as 2.5 cm with an uncertainty of 0.1 cm, what is the volume of the cube with its uncertainty?
A.
15.625 ± 0.25 cm³
B.
15.625 ± 0.5 cm³
C.
12.5 ± 0.1 cm³
D.
10.0 ± 0.2 cm³
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Solution
Volume = (2.5 cm)³ = 15.625 cm³. The uncertainty in volume can be calculated using the formula for propagation of uncertainty.
Correct Answer: A — 15.625 ± 0.25 cm³
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Q. If the length of a side of a square is doubled, what happens to the area? (2023)
A.
It remains the same
B.
It doubles
C.
It triples
D.
It quadruples
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Solution
Area of square = side². If side is doubled, new area = (2 * side)² = 4 * side², so area quadruples.
Correct Answer: D — It quadruples
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Q. If the length of a wire is doubled while keeping the cross-sectional area constant, how does its resistance change?
A.
Remains the same
B.
Doubles
C.
Halves
D.
Quadruples
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Solution
Resistance is directly proportional to length; doubling the length doubles the resistance.
Correct Answer: B — Doubles
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Q. If the length of a wire is doubled while keeping the cross-sectional area constant, how does its Young's modulus change?
A.
It doubles
B.
It halves
C.
It remains the same
D.
It quadruples
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Solution
Young's modulus is a material property and does not change with the dimensions of the wire.
Correct Answer: C — It remains the same
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Q. If the length of a wire is doubled while keeping the diameter constant, what happens to its resistance? (2019)
A.
It doubles
B.
It halves
C.
It quadruples
D.
It remains the same
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Solution
Resistance (R) is directly proportional to length (L). If length is doubled, resistance also doubles.
Correct Answer: A — It doubles
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Q. If the length of an object is doubled, what happens to its area?
A.
It remains the same
B.
It doubles
C.
It triples
D.
It quadruples
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Solution
If the length is doubled, the area increases by a factor of four (A = length²).
Correct Answer: D — It quadruples
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Q. If the length of an object is doubled, what happens to its volume?
A.
It remains the same
B.
It doubles
C.
It triples
D.
It increases by a factor of eight
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Solution
If the length is doubled, the volume increases by a factor of 2^3 = 8, since volume is proportional to the cube of the length.
Correct Answer: D — It increases by a factor of eight
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Q. If the length of the potentiometer wire is increased while keeping the voltage constant, what will happen to the balance point when measuring a cell's EMF?
A.
It will move to a longer length.
B.
It will move to a shorter length.
C.
It will remain unchanged.
D.
It will become unstable.
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Solution
Increasing the length of the potentiometer wire while keeping the voltage constant will increase the balance point length for the same EMF.
Correct Answer: A — It will move to a longer length.
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Q. If the length of the potentiometer wire is increased, what effect does it have on the maximum measurable voltage?
A.
It increases
B.
It decreases
C.
It remains the same
D.
It becomes zero
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Solution
Increasing the length of the potentiometer wire increases the maximum measurable voltage due to a larger potential gradient.
Correct Answer: A — It increases
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Q. If the lengths of the diagonals of a rhombus are 10 cm and 24 cm, what is the area of the rhombus?
A.
120 cm²
B.
240 cm²
C.
60 cm²
D.
300 cm²
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Solution
The area of a rhombus can be calculated using the formula (1/2) × d1 × d2 = (1/2) × 10 × 24 = 120 cm².
Correct Answer: B — 240 cm²
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Q. If the lengths of the semi-major and semi-minor axes of an ellipse are 5 and 3 respectively, what is the distance between the foci?
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Solution
The distance between the foci is given by 2c, where c = √(a^2 - b^2). Here, c = √(5^2 - 3^2) = √16 = 4, so the distance is 2c = 8.
Correct Answer: A — 4
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Q. If the lengths of the sides of a rectangle are 4 cm and 6 cm, what is its perimeter? (2022)
A.
20 cm
B.
24 cm
C.
10 cm
D.
12 cm
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Solution
Perimeter = 2 * (length + width) = 2 * (4 + 6) = 20 cm
Correct Answer: A — 20 cm
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Q. If the lengths of the sides of a triangle are 3 cm, 4 cm, and 5 cm, what type of triangle is it? (2023)
A.
Acute
B.
Obtuse
C.
Right
D.
Equilateral
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Solution
A triangle with sides 3 cm, 4 cm, and 5 cm satisfies the Pythagorean theorem (3² + 4² = 5²), thus it is a right triangle.
Correct Answer: C — Right
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Q. If the lengths of the sides of a triangle are 7 cm, 24 cm, and 25 cm, is it a right triangle? (2023)
A.
Yes
B.
No
C.
Cannot be determined
D.
Only if angles are known
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Solution
Using Pythagoras theorem, 7² + 24² = 49 + 576 = 625 = 25², so it is a right triangle.
Correct Answer: A — Yes
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Q. If the lengths of two sides of a triangle are 8 cm and 15 cm, what is the maximum possible length of the third side? (2021)
A.
22 cm
B.
23 cm
C.
24 cm
D.
25 cm
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Solution
The maximum length of the third side is less than the sum of the other two sides, so it can be 22 cm.
Correct Answer: A — 22 cm
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Q. If the lever arm is doubled while keeping the force constant, how does the torque change?
A.
It doubles
B.
It triples
C.
It remains the same
D.
It halves
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Solution
Torque is directly proportional to the lever arm; if the lever arm is doubled, the torque also doubles.
Correct Answer: A — It doubles
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Q. If the line 2x + 3y = 6 intersects the x-axis, what is the point of intersection?
A.
(3, 0)
B.
(0, 2)
C.
(0, 3)
D.
(2, 0)
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Solution
Setting y = 0 gives 2x = 6, thus x = 3. The point of intersection is (3, 0).
Correct Answer: A — (3, 0)
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Q. If the line 2x + 3y = 6 intersects the x-axis, what is the x-coordinate of the intersection point?
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Solution
Setting y = 0 gives 2x = 6, thus x = 3. The x-coordinate of the intersection point is 3.
Correct Answer: B — 2
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Q. If the line 3x + 4y = 12 intersects the x-axis, what is the point of intersection?
A.
(4, 0)
B.
(0, 3)
C.
(0, 4)
D.
(3, 0)
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Solution
Set y = 0 in the equation: 3x = 12 => x = 4. The point is (4, 0).
Correct Answer: A — (4, 0)
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Q. If the line 3x + 4y = 12 intersects the x-axis, what is the x-coordinate of the intersection point?
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Solution
Set y = 0 in the equation: 3x = 12 => x = 4.
Correct Answer: A — 4
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Q. If the line 3x + 4y = 12 intersects the y-axis, what is the point of intersection? (2021)
A.
(0, 3)
B.
(0, 4)
C.
(0, 2)
D.
(0, 1)
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Solution
Setting x = 0 gives 4y = 12, thus y = 3. The point of intersection is (0, 3).
Correct Answer: A — (0, 3)
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