Calculate oxidation number of C2H2O4

First You must know this

Oxidation number for H = + 1 and for O = - 2

let C unknown

the total charge for molecule is ZERO

SO = >> 2 (X) + 2 (+1) + 4 (-2) = 0 (0 - > for total charge)

so 2X + 2 + (-8) = 0

2X + 2 - 8 = 0 (Take 8 and 2 to another side and change the sign)

2X = 8 - 2 (Divide by 2 to calculate the value of x)

X = 8 - 2 : 2

X = 6 : 2 = 3

So the oxidation number for one Carbon is + 3, for two is + 6

2C = + 6, 2H = + 2, 4O = - 8 (the total Charge is ZERO (8-8 = 0)

GOOD LUCK