Series CHE/SP/1A Code No. SP/1-A · SP/1-A ©Educomp Solutions Ltd. 2014-15 OR CoSO 4 Cl.5NH 3 exists in two isomeric forms „A‟ and „B‟. Isomer „A‟ reacts with AgNO 3

Sample Paper (CBSE)

Series CHE/SP/1A Code No. SP/1-A

SP/1-A ©Educomp Solutions Ltd. 2014-15

CHEMISTRY

Time Allowed: 3 hours Maximum Marks: 70

General Instructions:

(i) All questions are compulsory.

(ii) Questions No. 1 to 5 are very short answer type questions and carry 1 mark

each.

(iii) Questions No. 6 to 10 are short-answer questions and carry 2 marks each.

(iv) Questions No. 11 to 22 are also short-answer questions and carry 3 marks

each.

(v) Questions No. 23 is a value based question and carry 4 marks.

(vi) Questions No. 24 to 26 are long-answer questions and carry 5 marks each.

(vii) Use Log Tables, if necessary. Use of calculators is not allowed.

1. Show the systematic alignment of magnetic moments of

antiferromagnetic substances.

2. What are the physical states of the dispersed phase and the

dispersion medium of sponge?

3. How can a lyophobic salt be protected?

4. Write the reaction involved in the extraction of silver after the

silver ore has been leached with NaCN.

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5. Which one of PCl4+ and PCl4

- is not likely to exist and why?

6. Explain the solubility rule “like dissolves like” in terms of

intermolecular forces that exist in solutions.

7. Write the rate equation for the reaction 2A + B C, if the order

of the reaction is zero.

8. Write two basic requirements for refining of a metal by Mond

process and by Van Arkel Method.

OR

How do we separate two sulphide ores by Froth Floatation

Method? Explain with an example.

9. Which is a stronger acid, phenol or cresol? Give reason.

10. What is meant by-

a. Peptide linkage

b. Biocatalyst

11. Give reason for the following:

a. Carbylamine reaction

b. Hofmann bromamide reaction

12. What is the significance of Henry‟s law constant KH?

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13. How can propan-2-one be converted into tert-butyl alcohol?

14. Why is NH2 group of aniline acetylated before carrying out

acetylation?

15. Amino acids behave like salts rather than simple amines or

carboxylic acids. Why?

16. How many tetrahedral voids are present per unit cell in a cubic

close packed structure? How will you show it?

OR

Calculate Avogadro‟s number if iron has a body centred cubic unit

cell with the cell dimension of 286.65 pm. Density of iron is 7.87 g

cm-3. Atomic mass of Fe is 56.0 u.

17. Rate law for the reaction A + 2B ⎯→ C is found to be

Rate = k [A][B]

If the concentration of reactant „B‟ is doubled, keeping the

concentration of „A‟ constant, what will be the value of rate

constant?

18. On the basis of Hardy Schulz rule, explain why the coagulating

power of phosphate is higher than chloride.

19. Out of H2O and H2S, which one has higher bond angle and why?

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20. Complete the following chemical equations:

a. P4 + NaOH + H2O

b. 2HI + H2SO4

c. Xe (g) [in excess] + F2 (g) ⎯⎯⎯⎯⎯⎯⎯

21. Name the following coordination entities and draw the structures

of their stereoisomers:

a. [Cr(C2O4)3]3-

b. [Pt(NH3)2Cl2]

c. [Co(NH3)3Cl3]

22. Which of the following compounds (a) and (b) will not react with a

mixture of NaBr and H2SO4? Explain why

a. CH3CH2CH2OH

b.

23. You are staying near a fertilizer factory. In the middle of the night

there is a leakage of ammonia which is detected by its smell.

Within 10 minutes you find the smell is intolerable.

a. What would you do as first aid against this gas spill accident

for self and neighbor?

b. What value do you derive from this?

24 a. What type of battery is the lead storage battery? Write the

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anode and cathode reactions and the overall reaction

occurring in a lead storage battery sending out an electric

current.

b. The resistance of a conductivity cell containing 0.001 M KCl

Electrode potential for Mg electrode varies according to the

solution at 298 K is 1500 Ω. What is the cell constant if the

conductivity of 0.001 M K solution at 298 K is

0.1146 x 10-3 S cm-1?

OR

a. A Voltaic cell is set up at 25oC with the half-cells

Ag+ (0.001 M) Ag and Cu2+ (0.10 M) Cu

What should be its cell potential? ( = 0.46 V, Log 105 = 5)

b. Electrode potential for Mg electrode varies according to the

Equation

= –

log

Draw the graph of and log .

25. a. In the titration of FeSO4 with KMnO4 in the acidic

medium, why is dilute H2SO4 used instead of dilute HCl?

b. Give reasons:

1. Among transition metals, the highest oxidation state is

exhibited in oxoanins of a metal.

2. Ce4+ is used as an oxidizing agent in volumetric analysis.

3. Transition metals form a number of interstitial compounds.

4. Zn2+ salts are white while Cu2+ salts are blue.

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OR

CoSO4Cl.5NH3 exists in two isomeric forms „A‟ and „B‟. Isomer „A‟

reacts with AgNO3 to give white precipitate, but does not react

with BaCl2. Isomer „B‟ gives white precipitate with BaCl2 but does

not react with AgNO3. Answer the following questions:

a. Identify „A‟ and „B‟ and write their structural formulas.

b. Name the type of isomerism involved.

c. Give the IUPAC name of „A‟ and „B‟.

26. a. Illustrate the following reactions giving a suitable chemical

equation for each:

1. Canizzaro reaction

2. Hell-Volhard-Zelinsky reaction

b. Draw the structures of the following compounds:

1. 3.Methylbutanal

2. Hexane-1, 6-dioic acid

3. P-Nitropropiophenone

OR

Write down functional isomers of a carbonyl compound with

molecular formula C3H6O. Which isomer will react faster with

HCN and why? Explain the mechanism of the reaction also. Will

the reaction lead to the completion with the conversion of whole

reactant into product at reaction conditions? If a strong acid is

added to the reaction mixture what will be the effect on

concentration of the product and why?

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1.

2. Solid, gas

3. By addition of lyophilic sol.

4. 4Ag(s) + 8NaCN(aq) + 2H2O(aq) + O2(g) 4Na[Ag(CN)2](aq) + 4NaOH(aq)

2Na[Ag(CN)2](aq) + Zn(s) Na2+[Zn(CN)4](aq) + 2Ag(s)

5. PCl4- is not likely to exist because PCl5 is stabler compound than PCl3.

6. A solute dissolves in a solvent if the intermolecular interactions are

similar in the two.

7. Rate = k

8. The Basic requirements for both processes are :

a. The metal should form a volatile compound with an available reagent.

b. The volatile compound should be easily decomposable, so that recovery

of metal is easy.

OR

Two sulphide ores can be separated by adjusting proportion of oil to water

or by using depressants. For example, in the case of an ore containing ZnS

ANSWERS


and PbS, the depressant NaCN is used. It forms complex with ZnS and

prevents it from coming with froth but PbS remains with froth.

9. Phenol is a stronger acid than cresol. CH3 group in phenol is electron

releasing.

10. a. Peptide linkage- Chemical bond formed between amino acids.

b. Biocatalyst- Catalyst that alters a biochemical reactions.

11. Write down the following:

a. Carbylamine reaction:

b. Hofmann bromamide reaction

R-CO-NH2 + Br2 + 4NaOH R-NH2 + Na2CO3 + 2NaBr + 2H2O

12. Higher the value of Henry‟s law constant KH, the lower is the solubility of

the gas in the liquid.

13. Using Grignard reagent

14. NH2 group of aniline is acetylated to shift the reaction on the right side.

15. In aqueous solution, the carboxyl group loses a proton and amino group

accepts a proton to form a zwitter ion.


16. Let us consider a unit cell of ccp or fcc lattice. The unit cell is divided into

eight small cubes. Each small cube has atoms at alternate corners In all,

each small cube has 4 atoms. When joined to each other, they make a

regular tetrahedron. Thus, there is one tetrahedral void in each small cube

and eight tetrahedral voids in total. Each of the eight small cubes have

one void in one unit cell of ccp structure. We know that ccp structure has 4

atoms per unit cell. Thus, the number of tetrahedral voids is twice the

number of atoms.

OR

Use the formula NA = zM/a3.d

17. The value of rate constant will be doubled.

18. According to Hardy Schulz rule, minimum quantity of an electrolyte

required to cause precipitation of a sol is called its coagulating value.

Greater the charge on flocculating ion and smaller is the amount of

electrolyte required for precipitation, higher is the coagulating power of

coagulating ion.

19. Bond angle of H2O is larger, because oxygen is more electronegative than

sulphur therefore bond pair electron of O–H bond will be closer to oxygen


and there will be more bond-pair repulsion between bond pairs of two O–H

bonds.

20. Complete the following chemical equations:

a. P4 + NaOH + H2O PH3 + NaH2PO2

b. 2HI + H2SO4 I2 + SO2 + 2H2O

c. Xe (g) [in excess] + F2 (g) ⎯⎯⎯⎯⎯⎯⎯ XeF2 (s)

21. Name the following coordination entities and draw the structures of their

stereoisomers:

a. [Cr(C2O4)3]3-

Trioxalato chromate(III)

b. [Pt(NH3)2Cl2]

Diamminedichloridoplatinum(II)

c. [Co(NH3)3Cl3]

Triamminetrichlorocobalt

22. Phenol will not react with a mixture of NaBr and H2SO4 as the activation

energy is not achieved.


23. a. Ammonia is highly soluble in water. It is detected by its characteristic

fishy odor. Hence keep a wet kerchief on your nose to stop inhaling the

gas. Then help your neighbours with your suggestion.

b. Alertness to tackle disasters for society.

24. a. Lead storage battery is commonly used in automobiles and invertors. It

consists of a lead anode and a grid of lead packed with lead dioxide

(PbO2) as cathode. A 38% solution of sulphuric acid is used as an

electrolyte. The cell reactions when the battery is in use are given

below:

Anode: Pb(s) + SO42–(aq) PbSO4(s) + 2e–

Cathode: PbO2(s) + SO42–(aq) + 4H+(aq) + 2e– PbSO4 (s) + 2H2O (l)

i.e., overall cell reaction consisting of cathode and anode reactions is:

Pb(s) + PbO2(s) + 2H2SO4(aq) 2PbSO4(s) + 2H2O(l)

b. Cell constant = 0.172 (Hint: G* = Rк)

OR

a. 0.312 V

b.

25. a. In the titration of FeSO4 with KMnO4 in the acidic medium, dilute

H2SO4 is used instead of dilute HCl because hydrochloric acid is

oxidised to chlorine.


b. Give reasons:

1. Due to half filled f-orbitals.

2. Ce4+ is used as an oxidizing agent in volumetric analysis as it has

half-filled f-orbitals that can accept electrons easily.

3. Transition metals form a number of interstitial compounds because

of small atoms occupy interstitial spaces in their compound.

4. Zn2+ salts are white while Cu2+ salts are blue because of the

frequency of light absorbed.

26. a. Illustrate the following reactions giving a suitable chemical 5 equation

for each:

1. Canizzaro reaction

2. Hell-Volhard-Zelinsky reaction

b. Draw the structures of the following compounds:

1. 3.Methylbutanal

(CH3)2CH2CHCHO

2. Hexane-1, 6-dioic acid

HOOC-(CH2)4-COOH


3. P-Nitropropiophenone

OR

CH3CH2CHO and CH3COCH3

Compound I will react faster with HCN due to less steric hinderance and

electronic reasons than II.

No, It is a reversible reaction. Hence equilibrium is established. Addition

of acid inhibits the reaction because the formation of –CN ions is

prevented.

Documents

Series CHE/SP/1A Code No. SP/1-A · SP/1-A ©Educomp Solutions Ltd. 2014-15 OR CoSO 4 Cl.5NH 3 exists in two isomeric forms „A‟ and „B‟. Isomer „A‟ reacts with AgNO 3