Among B2H6,B3N3H6,N2O,N2O4,H2S2O3 and H2S2O8, the total number of molecules containing covalent bond between two atoms of the same kind is ____
Answer: 4
Solution
Examining each molecule for bonds between two atoms of the same element:
B2H6: Contains B–H–B bridges, but no direct B–B bond. NO.
B3N3H6 (borazine): Alternating B–N bonds, no B–B or N–N. NO.
N2O: Contains N≡N bond. YES.
N2O4: Contains N–N bond linking two NO2 units. YES.