ISC 2014 Chemistry Practical Question Paper for Class 12

About this paper

This is ISC Class 12 Chemistry Paper 2 (Practical), code 862B, from the 2014 board examination. Three hours are allowed, plus fifteen minutes to read the paper, and all four questions are attempted in a separate answer booklet. Question 1 is a redox titration of sodium thiosulphate crystals, Na2S2O3·xH2O (25 g per litre), against potassium dichromate (5 g per litre), asking for both molarities, the molecular mass of the thiosulphate and the value of x. Question 2 is the identification of organic compounds C-16 and C-17. Question 3 is the qualitative analysis of C-18, which contains two anions and two cations; a qualitative analysis table is not allowed. Question 4 is the project and the chemistry practical file. This copy has the questions only.

Exam

ISC Class 12

Subject

Chemistry Practical

Year

2014

Paper code

862B

Time allowed

3 hours + 15 min reading

Questions

4

Pages

5

Answers included

No, questions only

Paper pattern

• Question 1

  Redox titration of sodium thiosulphate against potassium dichromate, with calculations of molarity and water of crystallisation

• Question 2

  5 marks

  Identification of two organic compounds, C-16 and C-17, from the tests given

• Question 3

  Qualitative analysis of substance C-18, which contains two anions and two cations

• Question 4

  Project and chemistry practical file, shown to the visiting examiner

Topics covered

• Redox titration
• Sodium thiosulphate and iodine
• Potassium dichromate
• Organic compound identification
• Fehling's test
• Qualitative analysis of anions
• Qualitative analysis of cations

Questions from this paper

1. C-10 is sodium thiosulphate crystals, Na2S2O3·xH2O, dissolved at 25 g per litre, and C-11 is potassium dichromate at 5 g per litre. Calculate the molarity of each solution, the molecular mass of the thiosulphate and the value of x.
2. For substance C-16, warm 1 ml with 1 ml of Fehling's solution, and in a separate test add alcoholic α-naphthol and pour concentrated sulphuric acid down the side of the tube. Identify the compound from your observations.
3. For substance C-17, record what happens with sodium hypochlorite, with acidified potassium dichromate, and with neutral ferric chloride after concentrated hydrochloric acid.
4. Analyse substance C-18 qualitatively. It contains two anions and two cations, and a qualitative analysis booklet or table may not be used.