GAGAN GANIT KNOWLEDGE FOUNDATION
II PUC CHEMISTRY (34)
I PREPARATORY EXAMINATION
SCHEME OF VALUATION
PART –A
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
(i)
(ii)
12
13.
3
Decreases.
Increases
Bimolecular reaction becomes kinetically first order when one of the reactants is in excess.
Tyndal effect
Tin (or other suitable example)
XeO3
It is due to symmetry of p-isomer which fits in crystal lattice better than the o-isomer.
Red –Brown precipitate
Functional differences between DNA and RNA
DNA
RNA
1. DNA is the chemical material of
1.RNA is not responsible for heredity
heredity
2.DNA molecules do not synthesise
2. Proteins are synthesized by RNA
proteins.
molecules in the cells.
(Any one)
PART-B
1M
1M
1M
1M
1M
1M
1M
1M
1M
Dipole-dipole interaction
Metallic bonding
1M
1M
1.
2.
3.
4.
5.
Nature of the electrolyte added.
Concentration of electrolyte.
Temperature.( it increases with the increase of temperature).
Nature of the solvent and its viscosity.
Size of the ions produced and their salvation. (Any two)
1M
2M
Rate constant for first order reaction is
[R ]0
2.303
log
t
[R ]
k
At t = t1/2 , [R] =
[ R ]0
2.303
log
t1/ 2
[ R ]0 / 2
k 
k
k
[ R ]0
2
1M
2.303
log 2
t1/ 2
2.303
 0.3010
t1/ 2
Or t 1 / 2  0.693
k
i.e for first order reaction, half life period is constant i.e. it is independent of initial
1M
concentration of the reacting species.
14.
Steady decrease in the size of lanthanoids with increase in atomic number is called
1M
lanthanoid contraction.
+3
1M
1
15.
Iodobenzene and Metanol
16.
Carboxylic acid reacts with ammonia produces acid amide.
1M
1M
1M
1M
(any other suitable example)
17.
The anionic detergents are sodium salts of sulphonated lengthy chain alcohols or 1M
hydrocarbons.
18.
Sodiun laurylsulphate or sodium dodecylbenzenesulphonate
1M
i) Used for the treatment of stress and mental disorder
1M
ii) Neutralize the stomach acidity
1M
PART-C
19.
1M
The bauxite ore, usually contains SiO2, iron oxides and titanium oxide (TiO2 ) as
impurities. Powdered bauxite ore is treated with a concentrated solution of NaOH at
473 – 523 K and 35 – 36 bar pressure. Al2O3 is converted sodium aluminate (and
SiO2 too as sodium silicate) leaving the impurities behind.
The aluminate solution is neutralised by passing CO2 gas and hydrated
20.
(i)
(ii)
1M
Al2 O3 is precipitated. A freshly prepared hydrated Al2O3 (seeding agent- which
induces the precipitation) is added. The sodium silicate remains in the solution and
hydrated alumina precipitates and is filtered, dried and heated to get pure Al2O3
1M
V2O5
1M
1M
Θ
2SO2(g)+ O2(g)
2SO3(g) ; ΔrH = −196.6 kJ mol
SO
+
H
SO
→
H
S
O
3
2
4
2
2
7
(iii)
21
(i)
−1
1M
O
P
H
(ii)
22.
(i)
(ii)
23.
(i)
(ii)
24.
(i)
H
OH
Bascity : 2
N2O or Dinitrogen oxide or Nitrigen(I) oxide
1M
1M
1M
By the action of HCl on KMnO4 liberates chlorine gas.
2KMnO4 + 16 HCl → 2KCl + 2MnCl2 + 8H2O + 5Cl2
bond in interhalogens is weaker than X − X bond in halogens. (Except F −
F bond)
1M
1M
1M
Cr2O72- + 2OH2CrO42- + 2H+
1M
1M
1M
5C2O42- + 2MnO4- + 16H+
2CrO42- + H2O
Cr2O72- + H2O
2Mn2+ + 8H2O + 10CO2↑
Small atoms such as hydrogen, carbon, boron and hydrogen are occupy the empty
spaces (interstitial sites) in lattices of transition metals is called interstitial
compound.
2
1M
1.
2.
3.
4.
25.
(i)
(ii)
Prperties:
They have high melting points, higher than those of pure metals.
They are very hard. Some borides are as hard as diamond.
They retain metallic conductivity.
They are chemically inert.
(any two)
dichloridobis(ethane-1,2-diammine)cobalt(III) chloride
Linkage isomerism arises in the compound containing ambidentate ligand (which can ligate
through two different atoms).
1M
1M
1M
(any other suitable examples)
26.
2M
sp3
Tetrahedral
Paramagnetic
1M
1M
1M
PART-D
27.
(i)
Let the unit cell edge length be ‘a’ and face diagonal AC = b.
1M
In Δ ABC
AC2 = b2 = BC2 + AB2= a2+a2 = 2a2
or
b =√ 2 a
If r is the radius of the sphere, we find
b = 4r =√ 2 a
Or
a= 4r/√ 2==2√ 2r
(we can also write, r= a/2 √2)
No of particles per unit cell=4
Total volume of four spheres = 4 × (4/3) πr3
Volume of the cube = a3 = (2√ 2r )3
Packing efficiency =
Volume occupied by four spheres in the unit cell
X100
1M
Total volume of the unit cell
4 × (4/3) πr3
=
------------------------
=
74%
1M
3
(ii)
(2√ 2r )
Number of corner particles A in FCC = (1/8)x8=1
Number of face center particles B in FCC =(1/2)x6=3
Formula of the compound - AB3
1M
1M
28.
(i)
(ii)
M2 =
𝑾𝟐 𝑹𝑻
1M
𝝅𝑽
1.26 𝑋 0.083𝑋300
M2 =
=
2.57𝑋10−3 𝑋 0.200
-1
= 61,022gmol
1M
1M
The partial pressure of the gas in vapour phase (P) is proportional to the mole
fraction of the gas (X) in the solution.
P = KHX
1M
3
1M
29.
(i)
(ii)
At anode: Pb(s) + 𝑆𝑂42− (aq)
At cathode:
+
PbO2(s) + 𝑆𝑂42− (aq) + 4𝐻(𝑎𝑞)
+ 2 e-
PbSO4 (s) + 2 e- (oxidation)
PbSO4 (s) + 2H2O(l) (reduction)
Overall
reaction
Pb(s) + PbO2(s) + 2H2SO4(aq)
2Fe3+ + 2e(-)
2Fe2+ or 2IHence for the given cell reaction n = 2
2 PbSO4 (s) + 2H2O(l)
I2 + 2e(-)
∆rGº = — nFEºcell
= - 2 × 96,487 C mol-1 × 0.236 V
= - 45,542 J mol-1
= - 45.542 k J mol-1
1M
1M
1M
}1
M
1M
30.
(i)
Given,
𝑘2
(𝑘1) = 2 , T1 = 27℃ = (27 + 273)K =300K
T2 = 37℃ = (37 + 273)K = 310K, R = 8.314 J K-1 mol-1
𝐸𝑎
(𝑘𝑘21) = 2.303𝑅
log 2 =
𝐸𝑎
𝑇1 𝑇2
310−300
2.303×8.314
300×310
0.3010 =
Ea =
𝐸𝑎
1M
10
2.303×8.314
300×310
0.3010 ×2.303 ×8.314 ×300 ×310
1M
10
Ea = 53,599 J mol-1 Or Ea = 53.99kJ mol-1
(1) Activation energy
(2) Proper orientation
(ii)
31.
(i)
1M
𝑇2 −𝑇1
log
1M
1M
Lyophobic sols
1. Irreversible
2. Unstable( needs stabilizing agents
for their preservation)
(ii) Emulsion are liquid-liquid colloidal systems, i.e., the dispersion of finely
divided droplets in another liquid.
Or
If a mixture of two immiscible or partially miscible liquids is shaken, a coarse
dispersion of one liquid in the other is obtained which is called emulsion.
Eg: Milk and Vanishing cream.
(iii) Greater the valence of the coagulating ion or f flocculating ion added, the
greater is its power to cause precipitation.
32.
(i)
Lyophillic sols
1. Reversible
2. Stable
CH3CH2CH2Cl
+
(b)
(CH3)3CBr
KOH
(c)
(ii)
Acetone
(a)
+
CH3CH2CH2OH +
CH3CH2CH2I
NaI
Ethanol
+
NaCl
2M
1M
1M
1M
1M
1M
(CH3)2C=CH2
CH3CH2CH2Cl + HCl +
SOCl2
SO2
Haloarenes reacts with sodium metal in presence of dry ether gives diphenyl.
4
1M
1M
1M
33.
(i)
(ii)
Primary alcohol + Lucas reagent
Turbidity occurs on heating or no
turbidity
Secondary alcohol + Lucas reagent
Turbidity occurs after five minutes
Tertiary alcohol + Lucas reagent
Turbidity occurs immidietly
Phenol reacts with chloroform and aq. NaOH followed by acidification produces
Salicylaldehyde.
1M
1M
1M
1M
1M
34.
(i)
When acetone is reduced using zinc amalgam in concentrated hydrochloric acid,
propane is formed.
O
Zn
H3C
(ii)
C
CH3 +
Hg conc HCl
4[H]
H3C
Propanone
CH2
1M
1M
CH3 + H2O
Propane
Benzene reacts with carbon monoxide and hydrogen chloride in the presence of
anhydrous aluminium chloride or cuprous chloride, (Cu2Cl2) benzaldehyde is
formed.
1M
CHO
1M
+
CO
HCl
Anhy AlCl3
Benzene
(iii)
But-2-enal.
1M
35.
(i)
Explanation
1M
1M
(any one equation)
(ii)
NH2
NO2
Fe/ HCl
N2Cl
NaNO2 / 2HCl
273-278K
Ethanol
3M
36.
(i)
2M
5
(ii)
In aqueous solution, the carboxyl group can lose a proton and amino group can
accept a proton, giving rise to a dipolar ion known as zwitter ion.
1M
NH3
R
(iii)
C
1M
COO
1M
H
Regulates the sugar level in body.
37.
(i)
(ii)
1M
Nylon6,6 or Nylon 6
H2C
Isoprene ( or 2-methyl-1, 3-butadiene)
(iii)
CH3
C C
H
2M
CH2
Interaction of hexamethylene diamine and adipic acid leading to the formation of
Nylon 6, 6.
n NH2(CH2)6NH2 + n HOOC(CH2)4COOH
Adipic acid
Hexamethylene
diamine
Polymerisation
H
H O
O
N (CH2)6 N C (CH2)4 C1M
Nylon 6,6
6
1M
n