Explanation

Stanley Miller in 1953, who was than a graduate student of Harold Urey (1893-1981) at the university of Chicago, demonstrated it clearly that ultra-violet radiation or electric discharges can produce complex organic compounds from mixture of $CH_{4},\ NH_{3},\ H_{2}O\$and$\ H_{2}$. The ratio of methane, ammonia and hydrogen in Miller’s experiment was 2 : 1 : 2