Everyday Science · Atoms, Elements & Compounds · page 15 of 30

Atoms MCQs with Answers

Includes 16 past paper MCQs (marked).

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Atoms MCQs (141–150)

10 MCQs with answers and a short one-liner. Hide answers to test yourself.

Past paper MCQs in this chapter · See all past papers

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141.
The period number in the periodic table tells?
Correct Answer: A. Number of shells
One-liner
The period number in the periodic table tells the number of shells (energy levels) an atom has.
142.
Which of the following transitions are NOT allowed in the normal electronic emission spectrum of an atom?
Correct Answer: A. 2s → 1s
One-liner
The transition 2s → 1s is NOT allowed because it violates the selection rule Δl = ±1 (s→s transitions have Δl = 0).
143.
Which of the following is a homo atomic molecule?
Correct Answer: C. H2
One-liner
A homo atomic molecule is composed of only one type of atom, and H2 is an example of such a molecule.
144.
Which of the following electron configurations represents the electron configuration for a magnesium cation (Mg²⁺)?
Correct Answer: B. 1s² 2s² 2p⁶
One-liner
The electron configuration of Mg²⁺ is 1s² 2s² 2p⁶, which is the same as the noble gas neon (Ne).
145.
Which is the most refined form of matter?
Correct Answer: C. Electron
One-liner
The most refined form of matter is the electron.
146.
The sum of protons and neutrons in the nucleus of an atom is known as ?
Correct Answer: C. Mass Number
One-liner
The sum of protons and neutrons in the nucleus of an atom is called the Mass Number.
147.
The maximum number of electrons the K orbit possesses?
Correct Answer: A. 2
One-liner
The K orbit (first energy shell) can hold a maximum of 2 electrons.
148.
An atom with 6 protons and 6 neutrons will have mass number ?
Correct Answer: D. 12
One-liner
The mass number is the sum of protons and neutrons, so an atom with 6 protons and 6 neutrons has a mass number of 12.
149.
Two fluorine atoms share one electron each in their outermost shell to achieve electronic configuration of ?
Correct Answer: B. Ne
One-liner
Two fluorine atoms share one electron each to achieve the electronic configuration of Neon (Ne).
150.
The maximum number of electrons in any shell is equal to ?
Correct Answer: C. 2n²
One-liner
The maximum number of electrons in any shell is equal to 2n², where n is the shell number.

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Atoms MCQs with Answers

Atoms MCQs (141–150)

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