Chemistry Test - 31

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Chemistry Test - 31

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Weekly Quiz Competition

Question 1
1 / -0

The maximum number of electrons in a Sub shell having the same value of spin quantum number is given by

A
l + 2

B
2l + 1

C
l (l + 1)

D
√l (l + 1)

Solution

Number of orbitals in a sub-shell = 2l + 1. Each of these can have one electron having the same value of spin.
Question 2
1 / -0

The I.U.P.A.C. name of is

A
1,2,3-propanetrinitrile

B
1,2,3- tricyanopropane

C
3 -cyano-1,5 -dinitrilepentane

D
3 -cyano -1,5 -pentanedinitriIe

Solution

3-Cyano-I, 5-pentadinitrile
Question 3
1 / -0

Directions: Based on following paragraph.
In certain polar solvents, \(\mathrm{PCl}_{\mathrm{s}}\) undergoes an ionization reaction in which \(\mathrm{Cl}^{-}\) ion leaves one \(\mathrm{PCl}_{5}\) molecule and attaches itself to another. \(2 \mathrm{PCl}_{5} \mathrm{PCl}_{4}^{+}+\mathrm{PCl}_{6}^{-}\)
Select incorrect statement (s).

A
The dissociation is a redox reaction

B
Hybridization changes from sp³d to sp³d² (PCl^-₆) and sp³ (PCl⁺₄)

C
Structure changes from trigonal bipyramidal to tetrahedral (PCl⁺₄) and octahedral (PCl⁻₆)

D
None of the above is incorrect

Solution

The reactions, in which one reactant is oxidized while the other is reduced, are called.
redox reactions. \(2 P \mathrm{Cl}_{5} \stackrel{+5}{\mathrm{PC}} l_{4}^{+}+\stackrel{+5}{\mathrm{PC}} l_{6}^{-}\) In the above reaction the oxidation state of P remains the same even after dissociation, thus, it is not a redox reaction, (every dissociation reaction is not a redox reaction) \(2 P C l_{5} P C l_{4}^{+}+P C l_{6}^{-}\) (trigonal \(s p^{3} d \quad s p^{3} \quad s p^{3} d^{2}\)
tipyramidal) (tetrahedral) (octahedral)
Question 4
1 / -0

The repeating units of acrilan are

A

B

C

D

Solution

Polyacrylonitrile (PAN), acrilan or orlon
hard used in preparing cloths, carpets.
Question 5
1 / -0

In the following 'compounds, the order of acidity is

A
III > IV > I > II

B
I > IV >III > II

C
II > I > III > IV

D
IV > III > I < II

Solution

-NO, group is electron withdrawing, and hence III and IV are strong acids whereas −CH₃ is electron releasing group, hence I is less acidic than the others.
Question 6
1 / -0

Which of the following does not contain P?O?P bond?

A
Isohypophosphoric acid

B
Diphosphorus acid

C
Diphosphoric acid

D
Hypophosphoric acid

Solution

Hypophosphoric acid \(\left(H_{4} P_{2} O_{6}\right)\)

Diphosphorus acid (Pyrophosphorus acid, \(H_{4} P_{2} O_{5}\) )

Diphosphoric acid (Pyrophosphoric acid, \(H_{4} P_{2} O_{5}\) )
Question 7
1 / -0

The solution containing 4.0 % PVC in one litre of dioxane was found to have osmotic pressure of 6.0 × 10⁻⁴ atm at 300 K. The molecular mass of polymer is

A
6.4 x 10²

B
3.0 x 10²

C
1.6 x 10⁵

D
5.6 x 10⁴

Solution
Question 8
1 / -0

Alcohols can be obtained from all methods except

A
hydroboration-oxidation

B
oxymercuration-demercuration

C
reduction of aldehyde/ketones with Zn-Hg/HCl

D
fermentation of starch

Solution

Reduction of aldehydes and ketones with Zn(Hg)/HCl yields alkanes - (Clemmensen reduction)
Question 9
1 / -0

The standard reduction potential for Cu²⁺ / Cuis + 0.34. Calculate the reduction potential at pH = 14 for the above couple. (K_spCu(OH)₂ = 1×10⁻¹⁹)

A
-0.22V

B
+ 0.22V

C
-0.44V

D
+0.44V

Solution

\begin{aligned}
&\text { [a] When } \mathrm{pH}=14\left[\mathrm{H}^{+}\right]=10^{-4} \text {and }\left[\mathrm{OH}^{+}\right]=11 \mathrm{M} \mathrm{K}_{s p}=\left[\mathrm{Cu}^{2+}\right]\left[\mathrm{OH}^{-}\right]^{2}=10^{-19}\\
&\therefore\left[C u^{2+}\right]=\frac{10^{-19}}{\left[O H^{-}\right]^{2}}=10^{-19} \text {The half cell reaction } C u^{2+}+2 e^{-} \rightarrow C u\\
&E=E^{o}-\frac{0.059}{2} \log \frac{1}{\left[C u^{2+}\right]}=0.34-\frac{0.059}{2} \log \frac{1}{10^{-19}}=-0.22 \mathrm{V}
\end{aligned}
Question 10
1 / -0

Adsorption occurs not due to

A
unbalanced force at surface molecules

B
unutilized free valencies at surface

C
increased entropy at surface

D
van der Waals' attraction at surface

Solution

Entropy (magnitude of randomness) decreases at surface during adsorption.