NEB Class 12 Chemistry case studies
NEB Class 12 Chemistry · Put your knowledge to work in context.
NEB Class 12 Chemistry (कक्षा १२ रसायन विज्ञान) is the chemistry paper within the Grade 12 examinations conducted by the National Examinations Board (NEB), Sanothimi, Bhaktapur, under the Government of Nepal. It is taken by Grade 12 science-stream students who need the subject for their School Leaving Certificate profile and for university admission in science, health, engineering and related fields. The NEB Class 12 Chemistry case studies are 5 cases and about 3,858 words.
1Choosing an Indicator for a Weak Acid–Strong Base Titration
In a Class 12 practical examination, a student must titrate 25.0 mL of 0.100 M acetic acid (Ka = 1.8 × 10−5 at 25 °C) with 0.100 M sodium hydroxide. Two indicators are on the bench: methyl orange (colour change pH 3.1–4.4) and phenolphthalein (pH 8.3–10.0).
697 words, about 3 min2Using Oxidised Mohr’s Salt to Standardise KMnO4
A bottle of Mohr’s salt, FeSO4·(NH4)2SO4·6H2O (molar mass 392 g mol−1), has stood open in a school store for several months. The pale green crystals are now coated with a brown solid, believed to be hydrated iron(III) oxide.
726 words, about 4 min3Identifying Propanal, Propanone and Ethanoic Acid with Limited Tests
Three reagent bottles in a school laboratory have lost their labels. The teacher says the contents are propanal, propanone, and ethanoic acid, one in each bottle.
794 words, about 4 min4EDTA Hardness Titration of a Borewell Water Sample
A 50.0 mL sample of borewell water is titrated with 0.0100 M EDTA at pH 10, using Eriochrome Black T as indicator. The mean titre is 12.4 mL.
826 words, about 4 min5Iodination of Propanone: Orders and Activation Energy
In a school laboratory, a student studies the acid-catalysed iodination of propanone at 25 °C by timing how long the iodine colour takes to disappear. The reaction mixture is made up so that propanone and HCl are in large excess compared with iodine.
815 words, about 4 min