Previous Year Question Papers NEET 2016 Phase II- Chemistry
13941.A given nitrogen-containing aromatic compound A reacts with Sn/HCl, followed by HNO2 to give an unstable compound B. B, on treatment with phenol, forms a beautiful coloured compound C with the molecular formula C12H10N2O. The structure of compound A is
13949.The decomposition of phosphine (PH3) on tungsten at low pressure is a first-order reaction. It is because the
Rate of decomposition is very slow
Rate is proportional to the surface coverage
Rate is inversely proportional to the surface coverage
Rate is independent of the surface coverage
Explanation:
Rate = k[PH3]
It is dependent on surface coverage because at low pressure, surface area covered is proportional to partial pressure of PH3 and it is first order w.r.t PH3.
θ = $\dfrac{kP}{1 + kP}$
θ = fraction of surface area covered at low pressure
θ = k P
13950.The coagulation values in millimoles per litre of the electrolytes used for the coagulation of As2S3 are given below:
I. (NaCl) = 52, II. (BaCl2) = 0.69 III. (MgSO4) = 0.22
The correct order of their coagulating power is
III > I > II
I > II > III
II > I > III
III > II > I
Explanation:
$Coagulation \ power \propto \dfrac{1}{Coagulation \ value}$
Higher the coagulation power, lower is the coagulation values in millimoles per litre.
MgSO4 > BaCl2 > NaCl.
13951.During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is
330 minutes
55 minutes
110 minutes
220 minutes
Explanation:
At Cathode:
At anode:
$\dfrac{W}{E} = \dfrac{It}{96500}$
0.1 × 2 = $\dfrac{3 × t(sec)}{96500}$
t = 6433 sec
t = 107.2 min
∼ 110 min.
13952.How many electrons can fit in the orbital for which n = 3 and l = 1 ?
14
2
6
10
Explanation: n = 3 l = 1
3p orbital can have only 2 electrons.
13953.For a sample of perfect gas when its pressure is changed isothermally from pi to pf, the entropy change is given by
$\triangle S = RT \ln \left(\dfrac{p_{i}}{p_{f}}\right)$
$\triangle S = nR \ln \left(\dfrac{p_{f}}{p_{i}}\right)$
$\triangle S = nR \ln \left(\dfrac{p_{i}}{p_{f}}\right)$
$\triangle S = nRT \ln \left(\dfrac{p_{f}}{p_{i}}\right)$
13956.In calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion (Ca2+) and fluoride ion (F–) are
4 and 8
4 and 2
6 and 6
8 and 4
Explanation:
Ca2+ is surrounded by 8F–
F– is surrounded by 4Ca+2
13957.If the $E_{cell}^0$ for a given reaction has a negative value, which of the following gives the correct relationships for the values of ΔG0 and Keq?
ΔG0 < 0; Keq < 1
ΔG0 > 0; Keq < 1
ΔG0 > 0; Keq > 1
ΔG0 < 0; Keq > 1
Explanation:
$E_{cell}^0$ < 0, so it is a non-spontaneous process
ΔG0 = – nFE0 = +ve, so ΔG0 > 0
ΔG0 = – 2.303RT log K
So, K < 1
13958.Which one of the following is incorrect for ideal solution?
ΔGmix = 0
ΔHmix = 0
ΔUmix = 0
ΔP = Pobs – Pcalculated by Raoults law = 0
Explanation:
For ideal solution inter molecular forces are identical so,
ΔHmix = 0, ΔUmix = 0, ΔGmix < O
So, 1st option is incorrect.
13959.The solubility of AgCl (s) with solubility product 1.6 × 10–10 in 0.1 M NaCl solution would be
Zero
1.26 × 10–5 M
1.6 × 10–9 M
1.6 × 10–11 M
Explanation:
AgCl ⇋ Ag+ + Cl–
Ag+ is S
Cl– is 0.1
Ksp = [Ag+] [Cl–]
1.6 × 10–10 = S × 0.1
1.6 × 10–9 = S
13960.Suppose the elements X and Y combine to form two compounds XY2 and X3Y2. When 0.1 mole of XY2 weights 10 g and 0.05 mole of X3Y2 weights 9 g, the atomic weights of X and Y are