What is the oxidation state of boron in a molecule of borax?

Borax is Na2B4O7. Let the oxidation state of boron be x. So, we know that the oxidation state of Sodium and Oxygen are respectively +1 and -2. So, {2×(+1)+4×(x) +7×(-2)} =0. =>2+4x-14=0. =>4x-12=0. =>4x=12. =>x=12/4. =>x=3. So, the oxidation state of boron in a molecule of borax is +3. read more

Borax is Na2B4O7. Let the oxidation state of boron be x. So, we know that the oxidation state of Sodium and Oxygen are respectively +1 and -2. So, {2×(+1)+4×(x) +7×(-2)} =0 =>2+4x-14=0 =>4x-12=0 =>4x=12 =>x=12/4 =>x=3. So, the oxidation state of boron in a molecule of borax is +3. read more

And since there are 13atoms in each molecule, and that many molecules present, the amountof atoms in a mole of Borax is (13 * 6.022E23 = 7.8*(10^24) atoms). If you're sure your teacher asked for atoms in a molecule, theanswer is 13, but I get the feeling you misread. read more