Question

which of the following molecules contains polar covalent bonds due to a significant difference in electronegativity between its atoms?
methane (ch4)
water (h2o)
oxygen gas (o2)
copper wire (cu)
how does the delocalized nature of electrons in metallic bonds contribute to the electrical conductivity of metals?
delocalized electrons are tightly bound and cannot move freely
metallic bonds do not involve electrons, so they do not contribute to conductivity
delocalized electrons can move freely throughout the metal lattice, carrying an electrical charge
the fixed positions of the metal ions allow for easy electron flow

Explanation:

1. For the first question, polar covalent bonds occur when there is a significant electronegativity difference between atoms. In water ($H_2O$), oxygen is more electronegative than hydrogen, creating polar covalent bonds. Methane ($CH_4$) has relatively small electronegativity differences between carbon and hydrogen, oxygen gas ($O_2$) has non - polar bonds as it is a homonuclear diatomic molecule, and copper wire is a metal with metallic bonds, not covalent bonds.
2. For the second question, the electrical conductivity of metals is due to the delocalized nature of electrons in metallic bonds. Delocalized electrons can move freely throughout the metal lattice, carrying an electrical charge.

Answer:

1. Water ($H_2O$)
2. Delocalized electrons can move freely throughout the metal lattice, carrying an electrical charge.