BCS Written Chemistry case studies
BCS Written Chemistry · Put your knowledge to work in context.
The BCS Written Chemistry examination is the descriptive, essay-type stage of the Bangladesh Civil Service (BCS) recruitment process for candidates who have already cleared the preliminary screening and are competing for cadre posts that require a chemistry background. It is intended for graduates in chemistry or closely related fields who can explain principles in continuous prose, not merely select options. The BCS Written Chemistry case studies are 5 cases and about 3,253 words.
1The Chlorine Dosage That Stopped Working
A municipal water treatment plant serving 250,000 people draws water from a river whose ammonia concentration has risen from 0.1 mg/L to 1.2 mg/L after upstream fertilizer runoff. Operators keep the free chlorine residual at 0.5 mg/L at the clear well, but consumer complaints of a persistent swimming-pool odour have tripled in a month, and bacteriological samples from two dead-end distribution mains show low-level coliform growth.
682 words, about 3 min2The Fertilizer Recommendation That Did Not Add Up
A rice farmer in Jessore applies urea at 250 kg/ha per season on the advice of a local dealer, who says "more nitrogen means more yield." The field has been continuously cropped for 12 years with no organic matter return; the soil pH has fallen from 6.5 to 5.2, and the farmer reports that yields have plateaued and even declined in the last two seasons despite the high urea rate. A soil test shows low cation exchange capacity, low available phosphorus, and low zinc.
643 words, about 3 min3Choosing an Analytical Method for Lead in Turmeric
A district food laboratory in Bangladesh receives complaints that turmeric powder from a market is unusually bright yellow. The suspicion is adulteration with lead chromate, a practice reported in South Asia to enhance colour.
679 words, about 3 min4The Exhausted Buffer in an Electroplating Bath
A small electroplating workshop in Dhaka plates steel parts with nickel from a Watts-type bath containing nickel sulfate, nickel chloride, and boric acid. The bath has operated for months without analysis.
648 words, about 3 min5The Reaction That Would Not Go to Completion
A final-year student attempts to synthesise ethyl acetate from ethanol and acetic acid using a sulfuric acid catalyst, refluxing for one hour, then distilling. The yield is disappointingly low, around 30%, and the distillate contains unreacted ethanol and acid.
601 words, about 3 min