CBSE Class 10 Science 2019 · Paper 31/2/2 · Question 3(a)

Electron dot structure: carbon ($2,4$) shares two pairs of electrons with each oxygen atom ($2,6$), so two shared pairs lie between carbon and each oxygen and each oxygen keeps two lone pairs: $\underset{\cdot \cdot }{\stackrel{\cdot \cdot }{O}}::\text{C}::\underset{\cdot \cdot }{\stackrel{\cdot \cdot }{O}}$ (see the figure). Every atom now has eight electrons in its outermost shell. Nature of bonding: the bonds are covalent (formed by sharing electrons); each carbon-oxygen bond is a double covalent bond, so the molecule is $\text{O}=\text{C}=\text{O}$.