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Question (31)

QN001871

The electricity in a Voltaic cell is produced due to

(A) friction
(B) magnetic force
(C) chemical reactions
(D) solar energy

Correct Answer: C

Explanation:

Chemical reactions inside the cell produce electric current.

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Question (32)

QN001872

A dry cell is called “dry” because its electrolyte is

(A) completely absent
(B) a solid metal rod
(C) thick moist paste
(D) pure water

Correct Answer: C

Explanation:

Dry cells contain paste-like electrolyte instead of liquid.

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Question (33)

QN001873

In a dry cell, the zinc container acts as the

(A) positive terminal
(B) negative terminal
(C) electrolyte
(D) carbon rod

Correct Answer: B

Explanation:

Zinc container forms the negative terminal of the dry cell.

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Question (34)

QN001874

Rechargeable batteries are preferred because they

(A) never wear out
(B) can be reused many times
(C) produce unlimited electricity
(D) contain no chemicals

Correct Answer: B

Explanation:

Rechargeable batteries can be charged and reused repeatedly.

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Question (35)

QN001875

A mobile phone battery requires charging more frequently after two years because

(A) its chemicals slowly wear out
(B) the charger becomes magnetic
(C) current stops flowing in wires
(D) the phone becomes heavier

Correct Answer: A

Explanation:

Rechargeable batteries lose efficiency after repeated charging cycles.

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Question (36)

QN001876

Which statement correctly compares electromagnets and permanent magnets?

(A) Both need electric current continuously
(B) Electromagnets can be switched OFF
(C) Permanent magnets lose magnetism instantly
(D) Electromagnets cannot attract iron

Correct Answer: B

Explanation:

Electromagnets work only when current flows and can be switched OFF.

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Question (37)

QN001877

Earth behaves like a giant magnet mainly because of

(A) forests on Earth
(B) movement of liquid iron inside Earth
(C) sunlight falling on Earth
(D) ocean waves

Correct Answer: B

Explanation:

Movement of liquid iron in Earth’s core creates magnetic field.

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Question (38)

QN001878

Migratory birds can navigate long distances because they use

(A) sound waves only
(B) Earth’s magnetic field
(C) rainfall patterns only
(D) moonlight only

Correct Answer: B

Explanation:

Many migratory birds use Earth’s magnetic field for navigation.

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Question (39)

QN001879

A student keeps the switch of an electromagnet ON for a long time. Later, the nail stops lifting clips though the wire is warm. Which is the best explanation?

(A) The battery may have weakened
(B) Iron clips became non-magnetic metals
(C) Wire changed into insulator
(D) Compass absorbed the current

Correct Answer: A

Explanation:

Weak battery reduces current and weakens the electromagnet.

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Question (40)

QN001880

Four coils of equal shape are made using iron, copper, aluminium, and nichrome wires. Current is passed through each. Compass needles near all coils show deflection because

(A) only iron can carry current
(B) all current carrying conductors produce magnetic field
(C) nichrome is a permanent magnet
(D) aluminium behaves like compass

Correct Answer: B

Explanation:

Every current carrying conductor produces magnetic effect.

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Question (31)

The electricity in a Voltaic cell is produced due to

Explanation:

Link:

Question (32)

A dry cell is called “dry” because its electrolyte is

Explanation:

Link:

Question (33)

In a dry cell, the zinc container acts as the

Explanation:

Link:

Question (34)

Rechargeable batteries are preferred because they

Explanation:

Link:

Question (35)

A mobile phone battery requires charging more frequently after two years because

Explanation:

Link:

Question (36)

Which statement correctly compares electromagnets and permanent magnets?

Explanation:

Link:

Question (37)

Earth behaves like a giant magnet mainly because of

Explanation:

Link:

Question (38)

Migratory birds can navigate long distances because they use

Explanation:

Link:

Question (39)

A student keeps the switch of an electromagnet ON for a long time. Later, the nail stops lifting clips though the wire is warm. Which is the best explanation?

Explanation:

Link:

Question (40)

Four coils of equal shape are made using iron, copper, aluminium, and nichrome wires. Current is passed through each. Compass needles near all coils show deflection because

Explanation:

Link:

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