Chemistry 0620 · IGCSE · Simple molecules and covalent bonds

Simple molecules and covalent bonds — practice question

The boiling point of methanal, $\text{CH}_2\text{O}$, is $-19\,^{\circ}\text{C}$. When the temperature is $-20\,^{\circ}\text{C}$, liquid methanal does not conduct electricity. In methanal, each carbon, hydrogen and oxygen atom has a noble gas electronic configuration. This configuration has been obtained by each atom in one of three ways: • gaining electrons • losing electrons • using shared electrons. Which statement explains the bonding between the carbon atom and the oxygen atom in methanal?

  • AThe carbon atom and the oxygen atom share four electrons.
  • BThe carbon atom and the oxygen atom share two electrons.
  • CCarbon is a negative ion and oxygen is a positive ion. These two ions attract each other.
  • DCarbon is a positive ion and oxygen is a negative ion. These two ions attract each other.

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