JEE Advanced 2018 · Paper 2 · Chemistry Q7

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ChemistryNumerical+3Question 25 of 54

The total number of compounds having at least one bridging oxo group among the molecules given below is ____.

$\mathrm{N_2O_3}$ , $\mathrm{N_2O_5}$ , $\mathrm{P_4O_6}$ , $\mathrm{P_4O_7}$ , $\mathrm{H_4P_2O_5}$ , $\mathrm{H_5P_3O_{10}}$ , $\mathrm{H_2S_2O_3}$ , $\mathrm{H_2S_2O_5}$

Your answer

Answer and worked solution

Official answer: 5

Check each structure for an X-O-X bridge:

Molecule	Structure	Bridging O?
$\ce{N2O3}$	$\ce{O=N-NO2}$ (N-N bond)	No
$\ce{N2O5}$	$\ce{O2N-O-NO2}$	Yes
$\ce{P4O6}$	six P-O-P bridges	Yes
$\ce{P4O7}$	six P-O-P bridges	Yes
$\ce{H4P2O5}$	$\ce{HP(O)(OH)-O-P(O)(OH)H}$	Yes
$\ce{H5P3O10}$	two P-O-P	Yes
$\ce{H2S2O3}$	$\ce{S=S(O)(OH)2}$	No
$\ce{H2S2O5}$	$\ce{HO-S(O)-S(O)2-OH}$ (S-S bond)	No

Total: 5. The key also accepts 6, which counts $\ce{N2O3}$ in its symmetric form $\ce{O=N-O-N=O}$ .

Answer: 5 (key: 5 or 6)

Topics:Oxoacids Covalent bonding and Lewis structures

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JEE Advanced 2018 · Paper 2, Chemistry question 7