A LevelChemistryCambridge (CIE)Exam Questions3. Chemical BondingDot & Cross Diagrams

Dot & Cross Diagrams (Cambridge (CIE) A Level Chemistry): Exam Questions

Exam code: 9701

36 mins13 questions

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Dot & Cross Diagrams

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1
1 mark

Ammonia, NH3, reacts with a proton, H+, to form ammonium, NH4+.

Using the following key:

• N electron

\times H electron

Which dot-and-cross diagram correctly illustrates the electron movement in this reaction?

  • Dot-and-cross diagram of NH3 reacting with H+, with a curly arrow drawn incorrectly from the H+ ion toward the nitrogen lone pair
  • Dot-and-cross diagram of NH3 reacting with H+, showing a curly arrow from the nitrogen lone pair to H+ forming a dative covalent bond in NH4+
  • Dot-and-cross diagram of NH3 reacting with H+ with no electron movement arrows shown
  • Dot-and-cross diagram of NH3 reacting with H+, with a curly arrow drawn incorrectly from the nitrogen atom representing hydrogen's electrons moving to H+

Choose your answer

2
1 mark

Which species contains an atom with an incomplete outer shell?

  • BF3

  • CH3-

  • H3O+

  • MgO

Choose your answer

3
1 mark

How many non-bonded, outer-shell electrons are present in one molecule of ammonia, NH3?

  • 0

  • 2

  • 5

  • 6

Choose your answer

1
1 mark

Which ion has a central atom with exactly three lone pairs of electrons?

  • BF2-

  • ClF2-

  • PF6-

  • SF5-

Choose your answer

2
1 mark

How many lone pairs of electrons are present on the central atom in a molecule of chlorine trifluoride, ClF3?

  • 0

  • 1

  • 2

  • 3

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3
1 mark

Which molecule obeys the octet rule?

  • BeCl2

  • BF3

  • CS2

  • PCl5

Choose your answer

1
1 mark

Calcium peroxide, CaO2, can be used in toothpaste as a teeth whitener.

Which dot-and-cross diagram represents the electron structure of the peroxide ion in CaO2?

Dot-and-cross diagrams A, B, C and D showing different possible electron structures for the peroxide ion

    Choose your answer

    2
    1 mark

    Which statement about 2-chloropropene, CH2=C(Cl)CH3, is not correct?

    • Every atom in the molecule obeys the octet rule

    • There are 24 valence electrons in the molecule

    • The molecule contains exactly one π bond

    • The chlorine atom has three lone pairs of electrons

    Choose your answer

    3
    1 mark

    The number of outer-shell electrons in elements X and Y are 5 and 7 respectively.

    What is the formula and the type of bonding in the compound formed between X and Y?

    • X3Y, covalent

    • X3Y, ionic

    • XY3, covalent

    • XY3, ionic

    Choose your answer