NEET-XI-Chemistry
exam-2 year:2016
- Qstn #165The van't Hoff factor (i) for a dilute aqueous solution
of the strong electrolyte barium hydroxide is
(1) 2
(2) 3
(3) 0
(4) 1digAnsr: 2Ans : (2)
Sol. Ba(OH)2 is strong electrolyte, so its 100% dissociation
occurs in solution
+ +22Ba OH Ba aq 2OH aq
Van't Hoff factor = total number of ions present in
solution i =3
- Qstn #166The percentage of pyridine (``C_5H_5N``) that forms
pyridinium ion (``C_5H_5N^+H``) in a 0.10 M aqueous
pyridine solution (``K_b`` for ``C_5H_5N`` = 1.7 × ``10^{-9}``) is
(1) 0.77%
(2) 1.6%
(3) 0.0060%
(4) 0.013%digAnsr: 4Ans : (4)
Sol. Pyridine (C5H5H5N) is a weak base
Kb = C2
=
91.7 10
0.1
= 41.30 10
= 4% 1.30 10 100
=% 0.013%
- Qstn #167In calcium fluoride, having the fluorite structure, the
coordination numbers for calcium ion (``Ca^{2+}) and
fluoride ion (``F^-``) are
(1) 8 and 4
(2) 4 and 8
(3) 4 and 2
(4) 6 and 6digAnsr: 1Ans : (1)
Sol. In CaF2, the coordination numbers for
Ca+2 = 8
=F 4
- Qstn #168If the E°cell for a given reaction has a negative
value,which of the following gives the correct
relationships for the values of ``\triangle G°`` and ``K_{eq}`` ?
(1) ``\triangle G°`` < 0; ``K_{eq}`` > 1
(2) ``\triangle G°`` < 0; ``K_{eq}`` < 1
(3) ``\triangle G°`` > 0; ``K_{eq}`` < 1
(4) ``\triangle G°`` > 0; ``K_{eq}`` > 1digAnsr: 3Ans : (3)
Sol. = 0cellE ve
∴▵ = 0 0cellG nF E
▵ = + &implies; ▵ 0G ve G 0
▵ = 0 eqG 2.303RTlogK
∴ eqK 1
- Qstn #169Which one of the following is incorrect for
ideal solution ?
(1) ``\triangle P = Pobs - P_{calculated by Raoult's law} = 0``
(2) ``\triangle G_{mix}`` = 0
(3) ``\triangle G_{mix}`` = 0
(4) ``\triangle U_{mix}`` = 0digAnsr: 2Ans : (2)
Sol. For an ideal solution ▵ =mixH 0
▵ =mixU 0
▵ mixS 0
According to ▵ = ▵ ▵mix mix mixG H T S
&implies; ▵ mixG 0
Incorrect answer, is ▵Gmix =0
- Qstn #170The solubility of AgCl(s) with solubility
product ``1.6 × 10^{-10}`` in 0.1 M NaCl solution
would be
(1) ``1.6 × 10^{-11}`` M
(2) zero
(3) ``1.26 × 10^{-5}`` M
(4) ``1.6 × 10^{-9}`` MdigAnsr: 4Ans : (4)
Sol.
+
+
+
+
+
+
NaCl aq Na (aq Cl aq
0.1M 0 0
0 0.1M 0.1 S
AgCl s Ag aq Cl aq
a 0 0
a S S S 0.1
Ksp = 1.6 × 10-10 = [Ag+] [Cl-] = S (0.1+S)
Ksp is small, S is neglected with respect to 0.1 M
1.6 × 10-10 = S × 0.1
S = 1.6 × 10-9 M
- Qstn #171Suppose the elements X and Y combine to form
two compounds ``XY_2`` and ``X_3Y_2``. When 0.1 mole of
``XY_2`` weighs 10 g and 0.05 mole of ``X_3Y_2`` weighs
9 g, the atomic weights of X and Y are
(1) 20, 30
(2) 30, 20
(3) 40, 30
(4) 60, 40digAnsr: 3Ans : (3)
Sol. Let atomic weight of x is Ax and y is Ay
= =
+2xy x y
10
n 0.1
A 2A
+ =x yA 2A 100 ...(1)
= =
+3 2x y x y
9
n 0.05
3A 2A
3Ax + 2Ay = 180 ...(2)
on solving eq. (1) and (2)
Ax = 40, Ay = 30
- Qstn #172The number of electrons delivered at the
cathode during electrolysis by a current of
1 ampere in 60 seconds is (charge on electron
= 1.60 × ``10^{-19}`` C)
(1) ``3.75 × 10^{20} ``
(2) ``7.48 × 10^{23}``
(3) ``6 × 10^{23}``
(4) ``6 × 10^{20}``digAnsr: 1Ans : (1)
Sol. Q = ne
i.t = n.e
= =
20
19
1 60
n 3.75 10
1.6 10
electrons
- Qstn #173Boric acid is an acid because its molecule
(1) accepts ``OH^-`` from water releasing proton
(2) combines with proton from water molecule
(3) contains replaceable ``H^+`` ion
(4) gives up a protondigAnsr: 1Ans : (1)
Sol. B(OH)3 + H2O [B(OH)4]- + H+
- Qstn #174``AlF_3`` is soluble in HF only in presence of KF. It is due
to the formation of
(1) ``AlH_3 ``
(2) ``K[AlF_3H]
(3) ``K_3[AlF_3H_3]``
(4) ``K_3[AlF_6]``digAnsr: 4Ans : (4)
Sol. AlF3 + 3KF K3[AlF6]
- Qstn #175Zinc can be coated on iron to produce galvanized
iron but the reverse is not possible. It is because
(1) zinc has lower negative electrode potential than
iron
(2) zinc has higher negative electrode potential than
iron
(3) zinc is lighter than iron
(4) zinc has lower melting point than irondigAnsr: 2Ans : (2)
Sol. Zinc has higher negative electrode potential than
iron, so iron cannot be coated on zinc.
- Qstn #176The suspension of slaked lime in water is
known as
(1) milk of lime
(2) aqueous solution of slaked lime
(3) limewater
(4) quicklimedigAnsr: 1Ans : (1)
Sol. Aqueous solution of slaked lime &implies;
lime water Suspension solution of slaked lime &implies; milk of lime
- Qstn #177The hybridizations of atomic orbitals of nitrogen
in ``NO_2^+``, ``NO_3^-``and ``NH_4^+`` respectively are
(1) ``sp, sp^2 and sp^3``
(2) ``sp^2, sp and sp^3``
(3) ``sp, sp^3 and sp^``2
(4) ``sp^2, sp^3 and sp``digAnsr: 1Ans : (1)
Sol. + =2NO sp Linear
= 23NO sp Trigonal planar
+ = 34NH sp Tetrahedral
- Qstn #178Which of the following fluoro-compounds is most
likely to behave as a Lewis base ?
(1) ``CF_4 ``
(2) ``SiF_4``
(3) ``BF_3``
(4) ``PF_3``digAnsr: 4Ans : (4)
Sol. PF3 act as Lewis base due to present of lone pair
on P atom.
- Qstn #179Which of the following pairs of ions is isoelectronic
and isostructural ?
(1)``SO_3^{2-} , NO_3^-``
(2)``ClO3^- , SO_3^{2-}``
(3) ``CO_3^{2-} , NO_3^-``
(4)``ClO3^- , CO_3^{2-}``digAnsr: 2Ans : (2 & 3)
Sol. (2) In 2
3 3SO ,ClO , No. of electrons = 42,
Shape : Pyramidal
(3) In 2
3 3CO ,NO , No. of electrons = 32
Shape : trigonal planar