JEE Advanced 2023 · Paper 2 · Chemistry Q10

ChemistryInteger+4Question 44 of 51

Consider the following molecules: $\ce{Br3O8}$ , $\ce{F2O}$ , $\ce{H2S4O6}$ , $\ce{H2S5O6}$ , and $\ce{C3O2}$ .

Count the number of atoms existing in their zero oxidation state in each molecule. Their sum is _____.

Your answer

Answer and worked solution

Official answer: 6

Assign oxidation states atom by atom from the structures.

$\ce{Br3O8}$ ( $\ce{O3Br-BrO2-BrO3}$ ): the terminal Br are $+6$ and the central Br is $+4$ . None is zero: 0.
$\ce{F2O}$ : O is $+2$ and F is $-1$ : 0.
$\ce{H2S4O6}$ (tetrathionic acid, $\ce{HO3S-S-S-SO3H}$ ): the two inner S are 0: 2.
$\ce{H2S5O6}$ (pentathionic acid): the three inner S are 0: 3.
$\ce{C3O2}$ ( $\ce{O=C=C=C=O}$ ): the central C is 0: 1.

Sum $=0+0+2+3+1=6$ .

JEE Advanced 2023 · Paper 2, Chemistry question 10