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53 Q 8 Topics Take Mock Test
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Difficulty: All Easy Medium Hard 41–50 of 53
Topics in General Science
Q.41 Medium Physics
The refractive index of a medium is 1.5. What is the speed of light in that medium? (c = 3 × 10⁸ m/s)
A 1.5 × 10⁸ m/s
B 2 × 10⁸ m/s
C 2.5 × 10⁸ m/s
D 3 × 10⁸ m/s
Correct Answer:  B. 2 × 10⁸ m/s
EXPLANATION

Refractive index n = c/v. Therefore, v = c/n = (3 × 10⁸)/1.5 = 2 × 10⁸ m/s.

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Q.42 Medium Physics
Which of the following elements has an electronic configuration of 2, 8, 7?
A Chlorine
B Bromine
C Fluorine
D Iodine
Correct Answer:  A. Chlorine
EXPLANATION

Chlorine (Cl) has atomic number 17, with electronic configuration 2, 8, 7 (K-shell: 2, L-shell: 8, M-shell: 7).

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Q.43 Medium Physics
A car moving at 72 km/h applies brakes and comes to rest in 8 seconds. What is the deceleration?
A 2.5 m/s²
B 2.0 m/s²
C 1.5 m/s²
D 3.0 m/s²
Correct Answer:  A. 2.5 m/s²
EXPLANATION

First convert 72 km/h = 20 m/s. Using v = u + at: 0 = 20 + a(8), so a = -20/8 = -2.5 m/s². Magnitude of deceleration is 2.5 m/s².

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Q.44 Medium Physics
A convex lens of focal length 20 cm is used as a magnifying glass. If an object is placed 5 cm from the lens, what is the nature of the image?
A Real, inverted, diminished
B Virtual, erect, magnified
C Real, erect, diminished
D Virtual, inverted, magnified
Correct Answer:  B. Virtual, erect, magnified
EXPLANATION

When object is between lens and focus (u < f), a convex lens produces virtual, erect, magnified image

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Q.45 Medium Physics
What is the young's modulus of a material?
A Stress/Strain
B Strain/Stress
C Force × Area
D Force/Volume
Correct Answer:  A. Stress/Strain
EXPLANATION

Young's modulus Y = Stress/Strain = (F/A)/(ΔL/L), a measure of material stiffness

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Q.46 Medium Physics
Which statement about elastic collisions is correct?
A Momentum is not conserved
B Kinetic energy is conserved
C Objects always stick together
D Maximum energy is lost
Correct Answer:  B. Kinetic energy is conserved
EXPLANATION

In elastic collisions, both momentum and kinetic energy are conserved

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Q.47 Medium Physics
A radioactive element has a half-life of 10 years. After 30 years, what fraction of the original sample remains?
A 1/2
B 1/4
C 1/8
D 1/16
Correct Answer:  C. 1/8
EXPLANATION

After 3 half-lives (30 years), the fraction remaining = (1/2)³ = 1/8

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Q.48 Medium Physics
A current-carrying conductor is placed in a magnetic field perpendicular to it. What force acts on it?
A Gravitational force
B Lorentz force
C Electrostatic force
D Frictional force
Correct Answer:  B. Lorentz force
EXPLANATION

The force on a current-carrying conductor in a magnetic field is called the Lorentz force, given by F = BIL

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Q.49 Medium Physics
A transformer has 500 turns in primary and 100 turns in secondary coil. If primary voltage is 220V, what is the secondary voltage?
A 44 V
B 1100 V
C 22 V
D 110 V
Correct Answer:  A. 44 V
EXPLANATION

Using transformer equation Vs/Vp = Ns/Np, we get Vs = 220 × (100/500) = 44 V

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Q.50 Medium Physics
An object is placed 30 cm in front of a concave mirror with focal length 10 cm. Where is the image formed?
A 15 cm behind the mirror
B 15 cm in front of the mirror
C 20 cm in front of the mirror
D 20 cm behind the mirror
Correct Answer:  B. 15 cm in front of the mirror
EXPLANATION

The mirror equation relates object distance, image distance, and focal length to locate where an image forms in a concave mirror.

Step 1: [Identify Given Values]

For this concave mirror problem, we extract the known measurements from the question.

\[\text{Object distance } (u) = 30 \text{ cm}\]
\[\text{Focal length } (f) = 10 \text{ cm}\]
\[\text{Image distance } (v) = ?\]
Step 2: [Apply Mirror Equation]

The mirror equation relates these three quantities and allows us to solve for the unknown image distance.

\[\frac{1}{f} = \frac{1}{u} + \frac{1}{v}\]

Substituting the values:

\[\frac{1}{10} = \frac{1}{30} + \frac{1}{v}\]
\[\frac{1}{v} = \frac{1}{10} - \frac{1}{30}\]
\[\frac{1}{v} = \frac{3}{30} - \frac{1}{30} = \frac{2}{30} = \frac{1}{15}\]
\[v = 15 \text{ cm}\]

Since v is positive, the image forms in front of the mirror (on the same side as the object).

The image is formed 15 cm in front of the mirror. Answer: (B)

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