Class-12 chemistry old question (question collection)

Shree Shanti Secondary School 

Nagarjun-04, Bafal, Kathmandu

The second terminal examination 2075

Grade: 12(Science)                   Subject: Chemistry                   F.M. 75

Time:  3hrs                                                                                   P.M. 30

Candidates are required to give their answer in their own words as far as practicable. The figures in the margin indicate full marks

Group : A (very short question)

Attempt any fifteen questions                       (15×2=30)

1) Why is NH₂ group of aniline protected before nitration?

2) What happens when chloroform is

            a) Treated with conc. Nitric acid

            b) Heated with silver powder

3) A haloalkane( M ) reacts with aq. NaOH to give isopropyl alcohol. What major product would you get when (M) is heated with Na in presence of dry ether?

4) Convert ethylamine to methylamine and vice versa.

5) Why is nucleophilic substitution difficult in haloarene?

6) What is the structure of isomeric alcohol ofC₃H₈O that gives iodoform test? Write the test reaction.

7) What is oxonium salt. Give an example.

8) Show your familiarity with cannizaro’s   reaction and aldol condensation.

9) How is phenol obtained from?

a) benzenediazonium chloride                      

b) Chlorobenzene

10) Which one has higher concentration and why?

a) 80gm/L NaOH solution or 3M NaOH solution.

b) 5.3 gm/L  Na₂CO₃  solution or 0.1N Na₂CO₃ solution.

11) Define pseudo order reaction. Give example.

12) How is Rinman's green prepared? Give its one important use.

13) Define extensive and intensive property with example.

14) Explain the effect of heat on blue vitriol.

15) State Hess's law of constant heat summation.

16) How can you distinguish acetaldehyde fromacetone?

17) Define galvanization and rusting.

18) Why is chloroacetic acid more acidic then acetic acid? Explain.

Group B (Short Question)

Attempt any five questions                            (5×5=25)

19)  How is aniline prepared in lab?

20)  A carbonyl compound (A) having molecular formula C₃H₆O is found to decolorize acidified KMnO₄ and responds to 2,4 DNP test. The compound doesn’t give iodoform test. Identify (A) giving the related reactions. How can the compound (A) be converted to ethane.

21) Define Gibb's free energy. How would you predict spontaneity of exothermic and endothermic reaction in terms of free energy change, entropy change and enthalpy change?

22)  Write the principle reaction for the lab preparation nitrobenzene. How would you show that nitro group of nitrobenzene is meta directing? Write the reduction product of nitrobenzene in alkaline medium.

23)  Define acidity of base. 0.4 gm of a divalent metal was dissolved in 50 cc of 1.28 N HCl solutions and was diluted to 100cc. 250 cc of this dilute solution required 54.6 cc of 0.11 N NaOH solutions for complete neutralization. Calculate the atomic mass of the metal.

24)  Explain the chemistry of white vitriol.

Group C (Long Question)

Attempt any two questions                                                     (2×10=20)

25) Describe Victor Meyer’s method to distinguish primary, secondary and tertiary alcohol. Convert-

a) Ethanal into propanone

b) Benzene into p- amino azobenzene

c) 1-propanol into 2-propanol

d) Benzene into phenol

e) Ethoxyethane into methoxyethane.

26)  a)Explain the manufacture of steel by Open Hearth process?

       b) differentiate order and molecularity of reaction? A first order reaction is 40% complete in 20 minutes. What fraction of reactant is consumed after 60 minutes.

27) Write a short note on.(any two)

a) Extraction of zinc

b) Lab preparation of aqueous formic acid                                       

c) Collision theory of bimolecular reaction.

d) Fermentation process

***Best of luck***