66th B.P.S.C. (Pre) 2020
The breath test conducted by police to check a drunken driver has which one of the following on the filter paper?
aPotassium dichromate-sulfuric acid✓ Correct
bPotassium permanganate-sulfuric acid
cSilica gel coated with silver nitrate
dTurmeric
eNone of the above / More than one of the above
Explanation
To test the breath of a person suspected of drunk driving, the police use an instrument called a breathalyzer (breathalyser). In this device, the filter paper/chemical cartridge contains potassium dichromate (K2Cr2O7) and sulfuric acid (H2SO4). The orange-red potassium dichromate reagent reacts with alcohol and turns green. The intensity of the green color is used to estimate the amount of alcohol in the exhaled breath.
general-science