AHSEC HS 2nd Year Question Paper 2023 Chemistry

ASSAM BOARD
QUESTION
PAPER
2023

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Total number of pages -16
33T CHEM

2023

CHEMISTRY
(Theory)
Full Marks : 70
Pass Marks : 21

Time : Three hours

The figures in the margin indicate full marks
for the questions.
General lnstructions :

() All questions are coipulsory.
(ü) Marks for each question are indicated against it.
(i) Answers slhould be specifie and to the point.
(iv) Question umbers 1 to consists of eigltt very slort
ansver type questions and carry 1mark eaclh. lx8 = 8
(v) Question numbers 9 to 18 are slortanswer type questions
Qnd carry 2 marks each. 2x10 = 20
(vi) Question numbers 19 to 27 are also slort answer type
questions and carry 3 marks each. 3x9 = 27
(vii) Question niunbers 28 to 30 are long answer type
questions and carry 3 marks ench. 5x3 = 15

Total = 70

Contd.

temperature and turns vellow on heating ?
1: Why ZnO is colourless at room 1

empty in a hexagonal closed packed
2. How much percentage of space is 1
Solid ?

Cl, from HCI by
3 Write the name of the catalyst used duringsynthesis of 1
Deacon's process.

1
4. Name the following chemical reaction :

ONa QH
cOOH
() CO, 400K J4-7,atm
(ii) Dil. HCI

5. Write two significances of Hoffmann bromamide degradation reaction.

6. Arrange the following in increasing order of their pK, values in aqueous
1
solution:

(C,H,), N, NH,, (C,H,), NH and C,H;NH,

33T CHEM [2]

7. Which of the following compound would undergo Cannizzaro reaction?

(a) Formaldehyde (RAfafsuu)
(b) Acetaldelhyde (afbbafoas)

Among the isomeric alkanes of molecular formula CsH12, identify the one
that on photochemical chlorination yields a single monochloride. 1

9. Element B crystallizes in body centered cubic (bcc) unit cell. Calculate
approximate number of unit cells in 9.2gm of element B. (Atomic number
of B = 23u) 2

BCAGA qP$ (O HRrs g â (bcc) FGE 21*| a o 9.2 gm B CTs |

OR/QT

The edge length of a face centered cubic cell of an ionic substance is
508 pm. If the radius of the cation is 110pm, then calculate the radius of
the anion. 2

J01Á 110 p1 , (U8 Q3CDK JIA (Ai |

10. What is meant by negative deviation from Raoule's law ? What type of
non-ideal solution is formed when ethanol is mixed with water ?
1+1=2

33T CHEM [3] Contd.

2
I1. The following limiting molar conductivity are given as
2 (H,SO4) =xS cm'mol

(Kso,)=yS.om'mol
m (CH,COOK)=zS cm'mol
Calculate limiting molar conductivity of acetic acid.

(H,SO,) =xS cm'mol

(K,SO4)= yScm'moll
m(CH,COOK)= zS cm²mot

OR/YA

The cell potential for the following cell is 0.576V at 298K. Calculate the pH
of the solution :

Pr|H, (9)]H (aq) Cu (0.01M) |Cu(s)
2
Given, 0.34V

P|H, (G) H(aq) Cu² (0.01M) |Cu(s)
0.34V

33T CHEM [4]

12 For the first order reaction A 2B, 1 mole of reactant Agives 0.4 moles
of B after 100 minutes. Caleulate the half life period of the reaction.
2

A ’ 2B, C pag a'aARNË 100 RG fE 0.4 T'a B BeA

OR/ W7

The decomposition of NH, on platinum surface is a zero order reaction.
What are the rates of productions of N2 and H, ifK= 2.5 x 10-41o1-Ls-l,.
2

caftata aU NH, RRIS aDi 4F1 afrt| 1R K= 2.5 x 10-*mol- Ls-1

13. Why is Cr* reducing and Mn3t oxidizing when both have d4
configuration? 2

OR/RAT

Out of Cut and Cu2*, which ion is more stable in aqueous solution and
why ? 2

14. Define atomisation enthalpy. Arrange the following in increasing order of
1+1=2
their atomisation enthalpy.
Mu, Fe, Zn

Mn, Fe, Zn

33T CHEM [5] Contd.

1+1=2
:
15. Answer the following questions

thefirst step in SN1 mechanism?
helpin 1
(a) How do polar solvents

product produced in the
structure of the major organic
(0) Write the
following reaction : CzH,OH/H,o 1

CH,CH,Il+ AgCN

AgCyCH;OH/H,O
CH,CH,I+
2
of HI with methoxyethane.
16. Write the mechanism of the reaction

can form intermolecular hydrogen
and alcohol
17, Both carboxylic acid of carboxylic acid is more than that of
bonding. But the boiling point 2
corresponding alcohol. Why?

compound with molecular formula CrCl,5H,0 precipitates
Acoordination structural formula of
18 two moles of AgClwith AgNO, solution. What is the 2
the compound ?

33T CHEM [6]

OR/ WIt

Draw the facial and meridional
isoner of the complex compound -
|co (NH,), (No,),1 2

[co (NH,, (NO,),)
19 Show that for the reactions of first order, half-life
period is
initial concentrations. What is the unit of rate constant ofindependent
of
a zero order
reaction ?
2+1=3

20. Answer the following questions : (any three) 1+1+1=3

(oY What is the effect of pressure on the adsorption of gases on solid ?
1

/6) Why are hydrophobic sols easily coagulated ? 1

(c) How do emulsifiers stabilize emulsions? 1

(d) Give an example of bio-chemical catalyst. 1

33T CHEM [7] Contd.

21. Answer the following questions

(a) The elevation in boiling point for 1 molal solution of non-volatile
solute Ais 3K and the depression in treezing point for 2 molal solution
of A in the same solvent is 6K. What is the ratio of Kh and K;?

(b) A gaseous mixture of two substances A and B, under a total pressure
of 0.8 atm is in eguilibrium with an 1deal liquid solution. If the mole
fraction of substanceA is 0.5 in the vapour phase and 0.2 in the liquid
phase, then calculate the vapour pressure of pure liquid A. 2

22. Why a solution of [Ni(H,O)12+ is green
while a 'solution of [Ni(CN)?- is
colourless? What is primary valency of Ni in Ni(CO)4] ? 2+1=3

INi(CO)4] Ni RS IJO fo?
23.
Answer the following questions : [Either (a) and (b) or
only (c)]

la) What will happen when vapour of 3°
copper at 573K? alcohol is passed over heated
1

33T CHEM
[8]

(b) How to get synthesize aspirin from salicylic acid ? 2

(c) How will you convert the following ? 1+1+1=3

(i)
Acetaldehyde to isopropanol
afscbatfvj
(i) Phenol to 2,4,6
tribromophenol
feeg 246 DEa1
(ii) Ethanol to chloroform

24. Answer the following questions : 1+1+1=3

Convert the following :

(i) Ethyl amine to Ethyl isocyanide

(ii) Aniline to p-Nitroaniline

(iii) Acetamide to Methyl amine

33T CHEM [9] Contd.

OR/WRT

1+1+1=3
Explain why:

() pK,value of aniline is more than that of methylamine.

(ii) Ethyl amine is soluble in water but aniline is not.

(i1) Aniline does not undergo Friedel-Craft reaction.

25. Answer the following questions :

(a) Which structure of protein is normally unaffected during denaturation
of protein? 1

OR/W
A non-reducing sugar on hydrolysis gives two reducing mono
saccharides. Write the name of the non-reducing sugar.

(b) Name the central metal ion present in Vitamin B12. 1

OR/ WI
Wh¡t pyrimidine bases are present in DNA?

33T CHEM [10]

(c) Why vitamins are also called coenzyme? 1

26. Answer the following questions

(a) Classify the following as addition and condensation polymers :
Thx4=2

Terylene (CORtA), Bakelite (AAaD), Polyvinyl Chloride (ffe~i
R5), Polythene (offR)
(b) Give an example of biodegradable aliphatic polyester. 1

OR/ WeAT

Which of the following polymer can be formed by using the following
monomer unit ? 1

NH

27. Three electrolytic cells A, Band Ccontaining electrolytes ZnSO4, AgNO3
and CaSO4 respectively were connected in series. A steady current of 1.5A
was passed through them and 1.45g Ag was deposited at the cathode of
cell B.

33T CHEM [11] Contd.

() How long did the Current flow? 1

(1) What mass of copper and zinc were deposited ?

(Given/a CE,
Atomic mass of / lsai CU= 63.5u, Zn=65.3u and Ag =108u
1+1=2

28. (a) Answer the following : (any three) 1x3=3

() Arrange the following compounds in increasing order of their
boiling points

H,S, H,0, H,Te, HSe
(ii) What is the number of
non-ionisable hydrogen atoms present in
the final product obtained fromn the hydrolysis ofPCl,?

(üi) What will form (mainly) when red phosphorus is heated in a
sealed tube at 803 K?

33T CHEM
[12|

(iv) Write the chemical formula of the Xenon compound which has
pyramidal structure.

(b) What will 1+1=2
happen, when (any two):
(i) Lead nitrate is heated at 673K.

(ii) XeF6 reacts with KF.

(111) Chlorine gas is passed through hot and concentrated NaOH
solution.

29. (a) Answer the following : 1+1+1=3

i) 1-Butyl bromide has higher boiling point than t-butyl bromide.
Why ?

(1) Arrange the following in increasing order of their rate towards
SNl reaction

CH, =CH - CH,-Ci, (CH3),CH-CI, CH, = CH - CH, -I

(iii)' Write the Finkelstein reaction.

33T CHEM [13 ] Contd.

OR/QIt
An alkyl chloride
(C;Hi,Cl) is an
Compound was treated with metallicoptically active compound. The
product on treatment with ethanol producemagnesium in ether and the
all the reactions and find out the 2-methyl-butane.
structure the
of
Write
alkvl chloride.
3

(b) Complete the following reactions 141-2

dry ether
. () 2> +2 Na

NO,
(i) Fe/ HCI
(i)
(i) HNO,/0-5° c

30. An organiccompound (A)with
molecular formula CgHgO
red precipitate (B) with Brady's reagent and forms an orange
(C) on heating with iodine in the presence of gives yellow precipitate
reduces Tollens' or Fehlings' reagent, nor doessodium hydroxide. It neither
it decolourise bromine water
or Baeyer's reagent. On drastic oxidation with
chromic acid, it gives
carboxylic acid (D) having molecular formula CzHO.
necessary chemical reactions and mark all compounds fromWrite all the
(A) to (D).
5

33T CHEM [14]

OR/
Complete the folowing reactions : 1+1+1+1+1=5

() H+
+ NH,-OH

ÇH,-CH,
(ii)
) KMnO, /OH
(i) H,o*

(ii) [Ag(NH)
CHO

Zn-Hg /HCI
(iv) CH,

() CH,MgBr lether
(o) CH, CH, CEN (i) H,0*

33T CHEM [ 15 ]