The electronegativity difference between a carbon atom 2.55 and a hydrogen atom 2.20 in a methane molecule can be calculated by subtracting the electronegativity of hydrogen from that of carbon:Electronegativity difference = Carbon electronegativity - Hydrogen electronegativityElectronegativity difference = 2.55 - 2.20Electronegativity difference = 0.35So, the electronegativity difference between carbon and hydrogen in a methane molecule is 0.35.