Chloroform is kept in dark coloured bottles because

Explanation

Chloroform in presence of air and sunlight oxidises slowly to form a highly poisonous compound , called phosegene or carbonyl choride.
`underset("chloroform")(2CHCHl_(3)) + underset("air")(O_(2)) overset(hv)to underset("Phosgene")(2 COCl_(2)) + 2HCl`
To avoid the oxidation of chloroform m it is kept in dark or yellow coloured bottles and filled upto brim.