Class 12 Chemistry Model Question 2078 New Syllabus

  Class 12 Chemistry Model Question Paper 2078 

According to New Course 2078




School Leaving Certificate Examination 2078

Grade: XII

Subject: Chemistry ; Subject Code: 302

Full marks: 75 (11 marks Obj+ 64 marks Sub)

Time: 3 Hours

Group A:

Multiple Choice Questions (11*1=11)

Time 25 Minutes

Tick the correct answer.

1.What is the equivalent weight of H3 PO3  the reaction;

2NaOH + H3 PO3  -- Na 2HPO3 + 2H2O

A) 2M

B) M/I

C) M/2


2. The solubility product of chalk is 9.3 * 10-8 What is its solubility in gram per liter?



C) 3.04 * 10-3

D) 3.04 * 10-4

3. What is the concentration of N2O5 in the following first order reaction in which the rate is 2.4 * 10-5 mol/L and rate constant is 3.0*10-5 S-1 ?

N2O5 ----- 4NO2 + O2

A) 0.04

B) 0.8

C) 1.2

D) 1.4

4. What happens when the lead storage battery is discharged?

A) SO2 is evolved

B) PbSO4 is consumed

C) Lead is formed

D) H2SO4 is consumed

5. What is the general electronic configuration of transition metal?

A) (n-1) s2p6d1 to 10 ns0 to 2

B) (n-1) s2p6ns2 np1

C) (n-1) s2p6d5 ns1

D) (n-1) s2p6 ns1

6. Which of the following ore is concentrated by forth-flotation process?

A) Hematite

B) Siderite

C) Galena

D) Malachite

7. Which of the following products is obtained when nitrobenzene is electrolytically reduced?

A) P-aminophenol

B) azobenzene

C) azoxybenzene

D) hydrazobenzene

8) Which of the following compounds is pi-bonded organo-metallic compound which has ethene as one of its component and is the first synthesized organometallic compound?

A) Zeise's salt

B) Ferrocene

C) Dibenzene chromium

D) Tetraethyl tin

9) What effects does calcium sulphate have on cement ?

A) Retards setting action

B) Acts as flux

C) Imparts color

D) Reduces strength

10. Removal of which of the following leads to higher fiber-fiber bonding strength in paper?

A) Softwood

B) Hardwood

C) Lignin

D) Pulp

11. In the figure given below which one is correct?

A) Alpha ray deviates towards A. beta rays deviate towards C and gamma rays direct towards B

B) Alpha rays direct towards B. beta rays deviate towards C and gamma rays towards A

C) Alpha rays deviate towards C, beta rays direct towards B and gamma rays towards A

D) Alpha rays deviate towards C, beta rays deviate towards A and gamma rays direct towards B.

 Model Question

School Leaving Certificate Examination 2078

Grade: XII

Subject: Chemistry

Subject Code: 302 Time: 3 Hours

Full :75(11 marks Obj+64 marks Sub)

Attempt all the questions.

Group B:

Short Answer Questions (8*5=40 )

1. Standard solution of Na2CO3 is used to determine the strength of during Titration.

A) How is the completion of the reaction in this titration detected? Is the solution prepared from Na2CO3 primary standard? Why? [1+1]

B)2.16 g of pure Na2CO3 is added to 400 ml deci-normal solution of H2SO4 . How many grams of H2SO4 is further required to neutralize the resultant solution completely? [3]

A) Derive the relation k = log 2.303/t *log a/(a - x). Show that for the first order reaction the time required for half the change (half life period) is independent of the initial concentration. (2+1) 

B) A first order reaction is 50% completed in 1.26*10145  How much time would it take for 90 % completion? (2)

2.Study the following data for the thermodynamic process

 H 2 O(l) -------------H 2 O(s) at different temperatures and at 1 atmospheric pressure.

a) Calculate the total entropy of the universe at given condition 3. (1)

b. Can we predict the spontaneity of the given reaction at 00 C?(1)

c. Calculate the equilibrium constant for the fusion of ice at 10 C . What is the effect of temperature for the entropy change of reaction? (2+1)


3. The figure shows the octahedral distortion of d-block orbital in the presence of ligand.

a) Why does octahedral disorder occur in the presense of ligand ? Explain on the basis of CFT ? (2)

b) On the basis of given distortion , how can you explain [ Cu(H20)6]++ is blue colored complex . (1)

c) Out of Fe++ and Fe+++ which one is more stable ? Explain on the basis of distortion seen in the above figure. (1)

d) why do such elements which give such splitting show good catalytic properties ? (1)

4. X is an ore of a metal M. X on calcination gives black precipitate (W) of metal oxide which belongs to group II of basic radical in qualitative analysis. X on roasting gives the metal (M) and a gas as major byproduct. The gas when passed through an acidified K2Cr2O7 solution turns green.

a. Identify the metal X. (1)

b. Write the reaction involved during calcination of X. (1)

c. Write the action of the gas on acidified K2Cr2O7 (1)

d. Convert metal X into it's vitriol. (2)

5. The given table shows the compounds and their molecular formula. How can you convert P to Q, where Q is a compound in which two methyl groups are substituted at adjacent carbons? How is P obtained from T, where T is secondary alcohol? Write the reactions involved in the conversion of P into R and S? [5x1=5]


An aromatic compound [A] in which one chlorine atom is substituted at benzene ring. When the compound [A] is heated with 2, 2, 2-trichloro ethanal in presence of conc. H2SO4 gives an insecticide [B] The compound [A] when treated with an acid chloride containing two carbon atoms in the presence of anhydrous AlCl3 , gives [C].

a. Identify B and C. (1+1)

b. Reaction of aq. NaOH on the compound [A] is more difficult than with chloroethane, justify with a suitable explanation. (2)

c. How would you obtain compound A from benzene diazonium chloride? (1)

6. A list of compounds are given as follows:

p-hydroxyazobenzene, C6H5N2Cl , C6H5NH2 , C6H5NO2 , C6H6

From the above list of compounds, prepare a sequence of reaction chain with suitable conditions and reactions. (1 + 1 + 1 + 1)


7. Write down the isomeric alcohols of C3H8O and their IUPAC name. How would you apply Victor Meyer's test to distinguish these isomers? (2+3)

8. A) Define condensation polymerization. Write the molecular structures monomers of Bakelite. (1+2)

B) Differentiate between OPC and PPC cement. (2)


Group C: 

Long Answer Questions ( 3*8=24)

9. (A) What amount of Zn(OH)2 will be precipitated out at 250 C if 100 ml of 0.22gm NaOH is added to 1 liter of a saturated solution of Zn(OH)2 ?Precipitate is obtained in this reaction. why?

[Solubility product of Zn(OH)2 at 2500 C is 1.8*10-14 .]

(B) Potassium hydroxide having pH 8 is diluted 1000 times. Calculate the pH of the diluted base. (3)


A)Calculate the heat of formation of ethyl alcohol from given data. (4)

B) The standard electrode potential for the following electrode reaction at standard state is

a. Write the cell notation indicating anode and cathode.  (1)

b. With IM solution of ion at 250 C and 1 atm. pressure, what will be the cell potential? (1)

c. Calculate the free energy change in the reaction. (1)

d. Can we store AgNO3 solution in a copper vessel? (1)

10, (A) A primary alcohol with molecular wt. 46 is boiled with sodium hydroxide and iodine. When the same alcohol is heated with ethanoic acid in presence of conc.H2SO4 , one of the derivatives of carboxylic acid is obtained. Write the reactions involved in both conditions.What would be the product obtained when the same alcohol is heated with Conc H2SO4 ?How would you distinguish the above alcohol from methanol? [1 + 1 + 1 + 1 + 1 = 5]

(B) An aromatic compound known as oil of mirabane is prepared from benzene. a. a.What product would you obtain when the compound is electrolyzed in acidic medium? (1)

b. Give the complete reaction for the conversion of the compound into yellow dye. (2)

11.(A) An organic compound is used in the given figure to preserve museum specimens and also to prepare urinary antiseptics.

a. Write the reaction when the compound is heated with concentrated sodium hydroxide. (1)

b. Draw the structure of urinary antiseptic (1)

c.Write the chemical reaction that would occur when the given preservative is treated with phenol in acidic medium. (2)

d. How would you obtain the preservative from methanol? (1)

(B) A carbonyl compound with molecular formula C3H6O (it does not give silver mirror test) has treated with a compound Y which gives Z. Z. on bydrolysis in acidic medium gives 2 hydroxy-2-methyl propanoic acid. Identify the carbonyl compound, Y and Z with proper reactions. [1+1+1] 


(A) Starting from compound P. how do the reactions proceed ahead to obtain T which gives benzene where R is aniline? Complete the reaction sequence with suitable conditions. [5x1=5]

(B) Arrange the given compounds according to their ascending order of acidic strength and justify your order.





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