A radioactive atom X emits a beta-particle. The resulting atom _?

C. Has an atomic number that is one more than that of X

A. Has the same atomic number as that of X

B. Has an atomic number that is one less than that of X

C. Has an atomic number that is one more than that of X

D. Has a mass number that is one less than that of X

Why do protons and electrons attract each other?

A. Because they have opposite charges

B. Because they have the same mass

C. Because they are both found in the nucleus

D. Because they both have neutral charge

Everyday Science · Atoms, Elements & Compounds · page 7 of 30

Atoms MCQs with Answers

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Atoms MCQs (61–70)

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61.
A radioactive atom X emits a beta-particle. The resulting atom _?
Correct Answer: C. Has an atomic number that is one more than that of X
One-liner
When a radioactive atom emits a beta-particle, its atomic number increases by one while its mass number remains unchanged.
62.
Who discovered the concept of atomic numbers?
Correct Answer: C. Moseley
One-liner
The concept of atomic numbers was discovered by Henry Moseley.
63.
The number of atoms in a molecule determine its ?
Correct Answer: C. Atomicity
One-liner
The number of atoms present in a molecule determines its atomicity.
64.
Which of the following is not a molecule?
Correct Answer: C. H
One-liner
H (hydrogen atom) is not a molecule because a molecule consists of two or more atoms chemically bonded together, whereas H is a single atom.
65.
A radioactive nuclide emits a β-particle. The atomic number (proton number) of the nucleus:
Correct Answer: A. Increases by 1
One-liner
When a radioactive nuclide emits a β-particle, the atomic number increases by 1 because a neutron is converted into a proton.
66.
Atomic number is represented by Z: it stands for _?
Correct Answer: B. Zahl
One-liner
The atomic number is represented by Z, which stands for the German word Zahl, meaning "number."
67.
Sodium has one electron in its outermost shell, so its valency is ?
Correct Answer: C. 1
One-liner
Sodium has one electron in its outermost shell, so its valency is 1.
68.
Why do protons and electrons attract each other?
Correct Answer: A. Because they have opposite charges
One-liner
Protons and electrons attract each other because they have opposite charges — protons are positively charged and electrons are negatively charged.
69.
In Na⁺ ion, number of electron is _?
Correct Answer: D. 10
One-liner
In Na⁺ ion, the number of electrons is 10.
70.
One atom of sodium is?
Correct Answer: B. 23 / Nₐ g
One-liner
One atom of sodium weighs 23 / Nₐ g, where Nₐ is Avogadro's number.

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Atoms MCQs with Answers

Atoms MCQs (61–70)

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