Roll No.
Series 08789
Code No. 043
Navodaya Vidyalaya Samiti
Chemistry (Theory) Sample Paper - 4
th
Class-12
Time allowed: 3 Hours
Maximum Marks: 70
General Instructions:
(i)
All questions are compulsory.
(ii)
Marks for each question are indicated against it.
(iii)
Questions number 1 to 8 are very short answer questions and carry 1 marks each.
(iv)
Questions number 9 to 18 are short answer questions and carry 2 marks each.
(v)
Questions number 19 to 27 are also short answer questions and carry 3 marks each.
(vi)
Questions number 28 to 30 are long answer questions and carry 5 marks each.
(vii)
Use Log Tables, if necessary. Use of calculators is not allowed.
Q1
Why is adsorption always exothermic?
1
Q2
Give two example of heterogeneous catalysis.
1
Q3
Write a name of metal, which is refined by the process Van-Arkel method.
1
Q4
Draw the structure of [Cr2O7]-2 ion.
1
Q5
Calculate magnetic moment of K4{Mn(CN)6} .
(Atomic number of Mn is 25)
1
Q6
Explain why dipole moment of chloro Benzene is lower than that of cyclohexyl
1
chloride?
Q7
Complete the reactions
1
HCHO + NaoH
1
Q8
How you will prepare phenyl isocynide from aniline?
Q9
Aluminium crystallises in cubie close-pack structure. Its metallic radius is 125 pm.
2
How many unit cells are there in 1 cm3 of alluminum.
Q10
Expalin the following terms with following exemples
2
1. Schottkydefect
2
2. F-centres
Q11
State henry’s law, mention its two important applications.
2
Q12
A solution of NI(NO3)2 is electrolysed between platinum electrodes using a surrent of
2
-1-
5 amp for 20 minutes. What mass of Ni is deposited at the cathode?
Q13
Distinguish between the meaning of terms adsorption and absorption.
2
Q14
Why copper matte is put in silicalined converter?
2
OR
What is the role of cryolite in the metallurgy of alluminium.
Q15
(a) Out of C6H5 CH2Cl and C6H5CHCl C6H5 which is more hydrolysed by aqueons
2
KOH.
(b) Para dichlorobenzane has higher melting point than those of ortho and meta
isomers discuss.
Q16
Primary alkyl halide (a) C4H9Br reacted with alcohoile KOH to give compound (b)
2
Compound b is reacted with HBr to gine(c) which is isomer of (a) when (b) was
reacted with sodium metal it gave a compound (d) C8H18 that was different that the
compound when n butyl bromide is reacted with sodium. Give the structrual formula
of (a) and write the eqation for all the reaction.
Q17
(a) Why vitamin C can not be stored in our body?
2
(b) What are the expected products of hydrolysis of lactose?
Q18
Explain the following terms.
(1) Denaturation
Q19
2
(2) Mutarotation
How many ml of 0.1 M HCl are required to react completely with 1 gm of mixture of
3
Na2Co3 and NaHCO3 containing equi molar amount of both?
Q20
What is electrochemical series? List its four important characteristies.
3
Q21
Write complete balanced chemical equation of the following
3
(a) P4 + KOH + H2O
(b) NaOH (Cold & dilute) + Cl2
(c) NH3 (excess) + Cl2
OR
(a) NaOH (Hot & Conc.) + Cl2
(b) NH3 + Cl2 (in excess)
(c) PH4 I + KOH
Q22
Explain why
3
(a) Transition metals have higher density than alkaline earth metals.
(b) Transtion metals exhibit higher enthalpy of automisation.
(c) Transition metals are used as catalyst.
-2-
Q23
(a) Write the mechanism of the reation when ethanol is heated with concentrated
3
H2SO4 at 443K.
(b) How you will get 2,4, 6 tribromophenol from phenol?
Q24
(a)Write short notes on the following name reactions.
3
(i) Hof mann’s bromidereaction
(ii) Carbylamine reaction
(b) How will you distinguish between aniline and benzylamine.
Q25
Write the names and structures of the monmers of the following polymers:
3
(a) Neoperene (b) Nylon-6 (c) Teflon
Q26
Explain the following with suitable examples.
3
(a) Cationic detergents
(b) Food preservatives.
(c) Artificial sweetening agents
Q27
(a) Write IUPAC name of linkege isomers of [Pt(NH3)2Cl No2].
3
(b) Using balance bond approach explain shape & magnetic behaviour of [Fe(CN)6]-3
ion.
Q28
(a) Define zero order reaction with at least two suitable examples.
5
(b) The following data were obtained during the first order thermal decomposition of
N2O5 (s) at constant volume
N2O5 (s)
2 N2O4(g) + O2(g)
Calculate the rate contents.
S. N.
Time/S
Total pressure (atm)
01
0
0.5
02
100
0.512
OR
(1) Define the following with suitable example
(a) Elementry reaction
(b) Order of reaction
(2) A first order reaction is 15% completed in 20 minutes. How long will it take to be
60% complete.
Q29
(a) Write the hybride state of central atom & shape of the following compounds in
each case
(a) IF5
(b) XeF4
-3-
5
(b) Give reason for the following
(i) NCl3 gets readly hydrolised while NF3 does not.
(ii) SF6 is known but SH6 is not known
(iii) HI is stronger acid than HCl
OR
(a) Write the hydride state of central atom & shape of the following compounds in
each case
(i) ClF3
(ii) XeF4
(b) Give reason for the following
(i)
PH3 is less basic than NH3.
(ii)
BiH3 is thermally less stable than SbH3
(iii)
HCl is weaker acid than HBr
Q30
a. Write IUPAC name of the following organic compounds
O
(1)
(2)
C
CHO
b. Give possible explanation
i.
Cyclohexanone forms cynohydrin in good yield but 2,2, 6 trimethyl cyclo
hexanone does not.
ii.
There are two NH2 groups in semicarbazide however only one is involved in
the formation of semicarbazone.
Give simple chemical test to distinguish between benzaldehyde & acetophenone.
OR
(a) Write IUPAC name of the following organic compounds.
(i)
(ii)
CH3
CHO
CH2OH
(b) Give possible explanation
(i)
(ii)
(iii)
Out of CH3COOH and CH2FCOOH which one is more acidic and why.
Out of C6H5CHO and CH3CHO which one is more reactive towards
nucluphillic addition reaction and why.
How will you distinguish pentane 3 one and pentane 2 one.
-4-
5