Octet Rule and its Exceptions Quiz

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Octet Rule And Its Exceptions Quiz - Quiz

Is your chemistry very strong? Do you think you know about different chemistry rules? Are you ready for the octet rule and its exceptions quiz that we have designed for you? The octet rule is one of the many chemical rules out there that says that atoms are the most stable, with their valence shells having eight electrons. Here are some questions for your practice about octet rules and their exceptions. Let's see how you perform.


Questions and Answers
  • 1. 

    This element loses 1 electron to attain an octet.

    • A.

      Potassium

    • B.

      Helium

    • C.

      Boron

    • D.

      None of these

    Correct Answer
    A. Potassium
    Explanation
    Potassium is the correct answer because it is an alkali metal with one valence electron in its outermost shell. In order to attain a stable octet, it loses this electron, resulting in a full outer shell with eight electrons. This loss of one electron allows potassium to achieve a stable electron configuration, making it more stable and less reactive.

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  • 2. 

    Incomplete octets are the molecules

    • A.

      With equal to 8 electrons surrounding the central atom

    • B.

      With more than 8 electrons surrounding the central atom

    • C.

      With less than 8 electrons surrounding the central atom

    • D.

      With 1 to 3 electrons surrounding the central atom

    Correct Answer
    C. With less than 8 electrons surrounding the central atom
    Explanation
    Molecules with less than 8 electrons surrounding the central atom have incomplete octets. This means that the central atom does not have a full valence shell of electrons, which is typically 8 electrons for most atoms. This can occur when the central atom forms bonds with other atoms, resulting in fewer than 8 electrons in its valence shell.

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  • 3. 

    Expanded octets are the molecules

    • A.

      With more than 8 electrons surrounding the central atom

    • B.

      With equal to 8 electrons surrounding the central atom

    • C.

      With 1 to 3 electrons surrounding the central atom

    • D.

      With 4 to 6 electrons surrounding the central atom

    Correct Answer
    A. With more than 8 electrons surrounding the central atom
    Explanation
    Expanded octets are molecules that have more than 8 electrons surrounding the central atom. In these molecules, the central atom can accommodate additional electrons in its valence shell by using its empty d orbitals, allowing for the formation of more than the usual 8 electron pairs. This phenomenon is commonly observed in elements from the third period onwards, such as sulfur, phosphorus, and chlorine. The expanded octet allows these elements to achieve a more stable electron configuration and form more bonds, increasing their bonding capacity and overall reactivity.

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  • 4. 

    Which of these is an exception to the octet rule?

    • A.

      Expended octet

    • B.

      Incomplete octet

    • C.

      Odd number octet

    • D.

      All of these

    Correct Answer
    D. All of these
    Explanation
    All of these are exceptions to the octet rule. The octet rule states that atoms tend to gain, lose, or share electrons in order to achieve a stable configuration with eight valence electrons. However, there are certain cases where atoms can have more or less than eight electrons in their valence shell. Expended octet refers to elements that can accommodate more than eight electrons in their valence shell, such as elements from the third period onwards. Incomplete octet refers to elements that have fewer than eight electrons in their valence shell, such as hydrogen and helium. Odd number octet refers to elements that have an odd number of valence electrons, such as nitrogen. Therefore, all of these options deviate from the octet rule.

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  • 5. 

    What is the molecule with unpaired electrons surrounding the central atom classified as?

    • A.

      Odd number electron

    • B.

      Even number electron

    • C.

      Complete electron

    • D.

      None of these

    Correct Answer
    A. Odd number electron
    Explanation
    A molecule with unpaired electrons surrounding the central atom is classified as having odd number electron. This means that the total number of electrons in the molecule is an odd number, with at least one electron being unpaired. This type of molecule is often referred to as a free radical, as the unpaired electron makes it highly reactive and prone to forming chemical bonds with other molecules in order to stabilize itself.

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  • 6. 

     Calcium (Ca) needs to lose _______ to become stable.

    • A.

      5

    • B.

      3

    • C.

      2

    • D.

      1

    Correct Answer
    C. 2
    Explanation
    Calcium (Ca) is an element with atomic number 20. It has 20 protons and 20 electrons. To become stable, it needs to achieve a full outer electron shell, which can be achieved by losing 2 electrons. This will result in a stable electron configuration similar to the noble gas argon (Ar) with 18 electrons in its outer shell.

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  • 7. 

    This element loses 2 electrons to attain an octet.

    • A.

      Magnesium

    • B.

      Lithium

    • C.

      Sulfur

    • D.

      Helium

    Correct Answer
    A. Magnesium
    Explanation
    Magnesium is the correct answer because it has two valence electrons in its outermost energy level. By losing these two electrons, magnesium achieves a stable octet configuration, similar to the noble gas neon. This electron loss allows magnesium to attain a full outer shell, making it more stable and less reactive.

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  • 8. 

    Which of these statements is true about the octet rule?

    • A.

      It focuses on an important chemical rule of thumb.

    • B.

      It says that the atoms that have bonded share eight outer electrons.

    • C.

      None of these two options is true.

    • D.

      Both A & B are true.

    Correct Answer
    D. Both A & B are true.
    Explanation
    The octet rule is an important chemical rule of thumb that states that atoms that have bonded share eight outer electrons. This rule helps in understanding the stability and reactivity of atoms and molecules. Both statements A and B are true, as they accurately describe the octet rule and its significance in chemistry.

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  • 9. 

    Which of the two elements, hydrogen and beryllium, have too few electrons to form an octet?

    • A.

      Hydrogen

    • B.

      Beryllium

    • C.

      Both

    • D.

      None

    Correct Answer
    C. Both
    Explanation
    Both hydrogen and beryllium have too few electrons to form an octet. An octet refers to having eight valence electrons in the outermost energy level. Hydrogen has only one electron, while beryllium has only two electrons. Therefore, neither of these elements can achieve a stable electron configuration by forming an octet.

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  • 10. 

    Which of these elements has too few electrons to form an octet?

    • A.

      Carbon Dioxide

    • B.

      Boron

    • C.

      Oxygen

    • D.

      None of these

    Correct Answer
    B. Boron
    Explanation
    Boron has too few electrons to form an octet. In its ground state, it has only three valence electrons. In order to achieve a stable electron configuration, it tends to lose or share electrons rather than gain the necessary five electrons to complete its octet. Therefore, boron is unable to form an octet. Carbon dioxide and oxygen, on the other hand, can both form octets by gaining or sharing electrons. The option "None of these" is incorrect as boron does not have enough electrons to form an octet.

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  • Current Version
  • Aug 16, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Dec 01, 2022
    Quiz Created by
    Keith Foster
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