Calculate the volume of `O_(2)` at STP required to burn completely 70 ml of acetylene.

Explanation

Combustion of acetylene is given as
`2C_(2)H_(2)+5O_(2) to 4CO_(2)+2H_(2)O`
2 moles of `C_(2)H_(5)-="5 moles of "O_(2)`
2 volume of `C_(2)H_(2)="5 volumes of "O_(2)`
2mL of `C_(2)H_(5)="5mL of "O_(2)`
Volume of oxygen required to burn 70mL of acetylene `=70 xx 5/2=175mL`