Global warming is due to increase of:

methane and \[{{O}_{2}}\] in atmosphere.

methane and nitrous oxide in atmosphere.

methane and \[C{{O}_{2}}\] in atmosphere.

methane and \[{{O}_{2}}\] in atmosphere.

Addition of phosphate fertilisers to water bodies causes:

Increase in amount of dissolved oxygen in water

Deposition of calcium phosphate

Greenhouse gases can be arranged in 'Global Warming Potential' sequence as

\[CFC>C{{O}_{2}}>{{N}_{2}}O>C{{H}_{4}}\]

\[{{N}_{2}}O>CFC>C{{H}_{4}}>C{{O}_{2}}\]

\[CFC>{{N}_{2}}O>C{{H}_{4}}>C{{O}_{2}}\]

\[CFC>C{{O}_{2}}>{{N}_{2}}O>C{{H}_{4}}\]

\[C{{O}_{2}}>CFC>{{N}_{2}}O>C{{H}_{4}}\]

Green chemistry means such reactions which:

Are related to the depletion of ozone layer.

Produce colour during reactions.

Reduce the use and production of hazardous chemicals.

Are related to the depletion of ozone layer.

The aromatic compounds present as particulates are

polycyclic aromatic hydrocarbons

Which of the following acts as a sink for CO?

Microorganisms present in the soil

Phosphate fertilizers when added to water leads to

increased growth of decomposers.

nutrient enrichment (eutrophication).

In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to

create potential difference between two electrodes

remove adsorbed oxygen from electrode surfaces

In the electrolysis of \[CuC{{l}_{2}}\] solution, the mass of the cathode increased by 3.2 g. What occured at the copper anode?

0.12 litre of \[C{{l}_{2}}\] was liberated

0.56 litre of \[{{O}_{2}}\] was liberated

0.1 mol \[C{{u}^{2+}}\] passed into the solution.

0.05 mol of \[C{{u}^{2+}}\] passed into the solution.

A solution contains \[F{{e}^{2+}},F{{e}^{3+}}\] and \[{{I}^{-}}\] ions. This solution was treated with iodine at\[35{}^\circ C\]. \[E{}^\circ \] for \[F{{e}^{3+}}/F{{e}^{2+}}\] is + 0.77 V and \[E{}^\circ \] for \[{{I}_{2}}/2{{I}^{-}}=0.536V.\] he favourable redox reaction is:

\[F{{e}^{2+}}\] will be oxidised to \[F{{e}^{3+}}\]

\[{{I}_{2}}\] will be reduced to \[{{I}^{-}}\]

There will be no redox reaction

\[{{I}^{-}}\] will be oxidised to \[{{I}_{2}}\]

\[F{{e}^{2+}}\] will be oxidised to \[F{{e}^{3+}}\]

\[{{\Lambda }_{ClC{{H}_{2}}COONa}}=224\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}},\]\[{{\Lambda }_{NaCl}}=38.2\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}},\]\[{{\Lambda }_{HCl}}=203\,oh{{m}^{-1}}c{{m}^{2}}ge{{q}^{-1}},\]What is the value of \[{{\Lambda }_{CIC{{H}_{2}}COOH}}\]

\[59.5\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]

\[288.5\,oh{{m}^{-1}}c{{m}^{2}}\,g\,e{{q}^{-1}}\]

\[289.5\,oh{{m}^{-1}}c{{m}^{2}}ge{{q}^{-1}}\]

\[388.8\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]

\[59.5\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]

Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is \[100\Omega .\]. The conductivity of this solution is \[1.29\text{ }S\text{ }{{m}^{-1}}\]. Resistance of the same cell when filled with 0.02 M of the same solution is \[520\Omega \]. The molar conductivity of 0.02 M solution of electrolyte will be

\[12.4\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

\[1.24\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

\[12.4\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

\[124\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

\[1240\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

A graph was plotted between molar conductivity of various electrolytes \[(NaCl,HCl\,and\,N{{H}_{4}}OH)\] and \[\sqrt{c}(in\,mol\,{{L}^{-1}}).\] Correct set is:

\[I\left( N{{H}_{4}}OH \right),II\left( NaCl \right),III,\left( HCl \right)\]

\[I(NaCl),II(HCL),III,(N{{H}_{4}}OH)\]

\[I\left( HCl \right),II\left( NaCl \right),III,\left( N{{H}_{4}}OH \right)\]

\[I\left( N{{H}_{4}}OH \right),II\left( NaCl \right),III,\left( HCl \right)\]

\[I(N{{H}_{4}}OH),II(HCl),III,(NaCl)\]

1.0 L each of a buffer containing 1 mole \[N{{H}_{3}}\] and 1 mol of \[NH_{4}^{+}\] were placed in the cathodic and anodic half-cells and 965 C of electricity was passed. If anodic and cathodic half cells reactions involve oxidation and reduction of water only as \[2{{H}_{2}}O\xrightarrow{{}}4{{H}^{+}}+{{O}_{2}}-4{{e}^{-}};\] \[2{{H}_{2}}O+2{{e}^{-}}\xrightarrow{{}}{{H}_{2}}+2O{{H}^{-}}\] Then pH of

both the solutions will increase

cathodic solution will increase

both the solutions will remain practically constant

both the solutions will increase

In the silver plating of copper, \[K[Ag{{(CN)}_{2}}]\] is used instead of \[AgN{{O}_{3}}\]. The reason is

a thin layer of Ag is formed on Cu

\[A{{g}^{+}}\] ions are completely removed from solution

less availability of \[A{{g}^{+}}\] ions, as Cu cannot displace Ag from \[{{[Ag{{\left( CN \right)}_{2}}]}^{-}}\] ion

When electric current is passed through a cell having an electrolytic solution, the cations move towards the cathode and anions towards the anode. If anode is pulled out from the solution

the cations and anions will move towards the cathode

the cations will continue to move towards cathode and anions will stop moving

both the cations and anions will stop moving

the cations and anions will start moving randomly.

1187 + Mcqs in Chemistry Page 8 McqOptions

351.	Global warming is due to increase of:
A.	methane and nitrous oxide in atmosphere.
B.	methane and \[C{{O}_{2}}\] in atmosphere.
C.	methane and \[{{O}_{2}}\] in atmosphere.
D.	methane and CO in atmosphere.
Answer» C. methane and \[{{O}_{2}}\] in atmosphere.

Discussion

352.	Addition of phosphate fertilisers to water bodies causes:
A.	Increase in amount of dissolved oxygen in water
B.	Deposition of calcium phosphate
C.	Increase in fish population
D.	Enhanced growth of algae
Answer» E.

Discussion

353.	Greenhouse gases can be arranged in 'Global Warming Potential' sequence as
A.	\[{{N}_{2}}O>CFC>C{{H}_{4}}>C{{O}_{2}}\]
B.	\[CFC>{{N}_{2}}O>C{{H}_{4}}>C{{O}_{2}}\]
C.	\[CFC>C{{O}_{2}}>{{N}_{2}}O>C{{H}_{4}}\]
D.	\[C{{O}_{2}}>CFC>{{N}_{2}}O>C{{H}_{4}}\]
Answer» C. \[CFC>C{{O}_{2}}>{{N}_{2}}O>C{{H}_{4}}\]

Discussion

354.	Synthesis of ethanal commercially from which of the following reagent is the part of green chemistry?
A.	\[C{{H}_{3}}C{{H}_{2}}OH\]
B.	\[C{{H}_{2}}=C{{H}_{2}}\]
C.	\[HC\equiv CH\]
D.	All of these
Answer» C. \[HC\equiv CH\]

Discussion

355.	Use of which of the following solvent in dry cleaning will result in less harm to ground water?
A.	\[C{{l}_{2}}C=CC{{l}_{2}}\]
B.	Liquid \[C{{O}_{2}}\]
C.	\[{{H}_{2}}{{O}_{2}}\]
D.	None of these
Answer» C. \[{{H}_{2}}{{O}_{2}}\]

Discussion

356.	Green chemistry means such reactions which:
A.	Produce colour during reactions.
B.	Reduce the use and production of hazardous chemicals.
C.	Are related to the depletion of ozone layer.
D.	Study the reactions in plants.
Answer» C. Are related to the depletion of ozone layer.

Discussion

357.	BOD is connected with
A.	microbes and organic matter.
B.	organic matter.
C.	microbes.
D.	None of the above
Answer» B. organic matter.

Discussion

358.	The aromatic compounds present as particulates are
A.	polycyclic aromatic hydrocarbons
B.	benzene
C.	toluene
D.	nitrobenzene
Answer» B. benzene

Discussion

359.	Which of the following acts as a sink for CO?
A.	Plants
B.	Haemoglobin
C.	Microorganisms present in the soil
D.	Oceans
Answer» D. Oceans

Discussion

360.	Which of the following is most abundant hydrocarbon pollutant?
A.	Butane
B.	Ethane
C.	Methane
D.	Propane
Answer» D. Propane

Discussion

361.	The region which is greatly affected by air pollution is
A.	thermosphere
B.	stratosphere
C.	troposphere
D.	mesosphere
Answer» D. mesosphere

Discussion

362.	Water sample is reported to be highly polluted if BOD (Biological Oxygen Demand) value of sample becomes
A.	more than 17 ppm.
B.	equal to 10 ppm.
C.	equal to 5 ppm.
D.	less than 5 ppm.
Answer» B. equal to 10 ppm.

Discussion

363.	Photochemical smog consists of excessive amount of X, in addition to aldehydes, ketones, peroxyacetyl nitrate (PAN), and so forth X is:
A.	CO
B.	\[C{{H}_{4}}\]
C.	\[{{O}_{3}}\]
D.	\[C{{O}_{2}}\]
Answer» D. \[C{{O}_{2}}\]

Discussion

364.	Minamata disease of Japan is due to pollution of
A.	Aresenic
B.	Lead
C.	Cyanide
D.	Mercury
Answer» E.

Discussion

365.	Phosphate fertilizers when added to water leads to
A.	increased growth of decomposers.
B.	reduced algal growth.
C.	increased algal growth.
D.	nutrient enrichment (eutrophication).
Answer» E.

Discussion

366.	The emf of the cell \[Pt\,C{{l}_{2}}(g)({{P}_{1}}atm)/C{{l}^{-}}(aq)\]\[(1M)/C{{l}_{2}}(g)({{P}_{2}}atm)Pt\] will be positive when
A.	\[{{P}_{1}}={{P}_{2}}\]
B.	\[{{P}_{1}}<{{P}_{2}}\]
C.	\[{{P}_{1}}>{{P}_{2}}\]
D.	None of these
Answer» C. \[{{P}_{1}}>{{P}_{2}}\]

Discussion

367.	The solution of \[CuS{{O}_{4}}\] in which copper rod is immersed is diluted to 10 times. The reduction electrode potential
A.	Increases by \[30m\text{ }V\]
B.	Decreases by \[30m\text{ }V\]
C.	Increases by \[59m\text{ }V\]
D.	Decreases by \[59m\text{ }V\]
Answer» C. Increases by \[59m\text{ }V\]

Discussion

368.	The \[E{{{}^\circ }_{{{M}^{3+}}/{{M}^{2+}}}}\] values for \[Cr,Mn,Fe\] and Co are \[-0.41,+1.57,+0.77\] and + 1.97V respectively For which one of these metals the change in oxidation state from +2 to +3 is easiest?
A.	Fe
B.	Mn
C.	Cr
D.	Co
Answer» D. Co

Discussion

369.	In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to
A.	produce high purity water
B.	create potential difference between two electrodes
C.	generate heat
D.	remove adsorbed oxygen from electrode surfaces
Answer» C. generate heat

Discussion

370.	The standard reduction potentials at \[25{}^\circ C\] of \[L{{i}^{+}}/Li,B{{a}^{2+}}/Ba,N{{a}^{+}}/Na\] and \[M{{g}^{2+}}/Mg\] are \[-3.03,-2.73,-2.71\] and \[-2.37\] volt respectively Which one of the following is the strongest oxidising agent?
A.	\[N{{a}^{+}}\]
B.	\[L{{i}^{+}}\]
C.	\[B{{a}^{2+}}\]
D.	\[M{{g}^{2+}}\]
Answer» E.

Discussion

371.	\[{{I}_{2}}(s)\|{{I}^{-}}(0.1M)\] half-cell is connected to a \[{{H}^{+}}\left( aq \right)\left\| {{H}_{2}}\left( \text{1}bar \right) \right\|Pt\] half cell and e.m.f. is found to be\[0.7714V.if\,{{E}^{{}^\circ }}_{{{I}_{2}}\|{{I}^{-}}}=0.535\text{ }V\], find the pH of \[{{H}^{+}}\|{{H}_{2}}\] half-cell.
A.	1
B.	3
C.	5
D.	7
Answer» C. 5

Discussion

372.	Equivalent conductance at infinite dilution, \[{{\lambda }^{{}^\circ }}\] of \[N{{H}_{4}}Cl,\,NaOH\] and \[NaCl\] are 128.0,217.8 and \[109.3\text{ }oh{{m}^{-1}}c{{m}^{2}}\text{ }e{{q}^{-1}}\] respectively. The equivalent conductance of \[0.01\text{ }N\text{ }N{{H}_{2}}OH\] is \[9.30\text{ }oh{{m}^{-1}}\,c{{m}^{2}}\text{ }e{{q}^{-1}}\] then the degree of ionization of \[N{{H}_{4}}OH\] at this temperature would be
A.	0.04
B.	0.1
C.	0.39
D.	0.62
Answer» B. 0.1

Discussion

373.	The resistance of 1 N solution of acetic acid is 250 ohm, when measured in a cell of cell constant\[1.15\text{ }c{{m}^{-1}}\]. The equivalent conductance (in \[oh{{m}^{-1}}c{{m}^{2}}equi{{v}^{-1}}\]) of 1 N acetic acid will be
A.	4.6
B.	9.2
C.	18.4
D.	0.023
Answer» B. 9.2

Discussion

374.	\[A{{l}_{2}}{{O}_{3}}\] is reduced by electrolysis at low potentials and high currents. If \[4.0\times {{10}^{4}}\] amperes of current is passed through molten \[A{{l}_{2}}{{O}_{3}}\] for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency. At. mass of\[Al=27g\text{ }mo{{l}^{-1}}\])
A.	\[8.1\times {{10}^{4}}g\]
B.	\[2.4\times {{10}^{5}}g\]
C.	\[1.3\times {{10}^{4}}g\]
D.	\[9.0\times {{10}^{3}}g\]
Answer» B. \[2.4\times {{10}^{5}}g\]

Discussion

375.	How long a current of 3 amperes has to be passed through a solution of \[AgN{{O}_{3}}\] to coat a metal surface of \[80c{{m}^{2}}\] and 0.005 mm thick layer. Density of Ag is \[10.5\text{ }g\,c{{m}^{-3}}\]
A.	125.1 seconds
B.	12.5 seconds
C.	155.2 seconds
D.	200 seconds
Answer» B. 12.5 seconds

Discussion

376.	Among the following cells: (I) Leclanche cell (II) Nickel-Cadmium cell (III) Lead storage battery (IV) Mercury cell primary cells are
A.	I and II
B.	I and III
C.	II and III
D.	I and IV
Answer» E.

Discussion

377.	Which of the following is a highly corrosive salt?
A.	\[H{{g}_{2}}C{{l}_{2}}\]
B.	\[HgC{{l}_{2}}\]
C.	\[FeC{{l}_{2}}\]
D.	\[PbC{{l}_{2}}\]
Answer» C. \[FeC{{l}_{2}}\]

Discussion

378.	Electrode potentials \[\left( E{}^\circ \right)\] are given below: \[C{{u}^{+}}/Cu=+0.52V,\] \[F{{e}^{3+}}/F{{e}^{2+}}=+0.77V,\] \[\frac{1}{2}{{I}_{2}}(s)/{{I}^{-}}=+0.54V,\] \[A{{g}^{+}}/Ag=+0.88V\]. Based on the above potentials, strongest oxidizing agent will be:
A.	\[C{{u}^{+}}\]
B.	\[F{{e}^{3+}}\]
C.	\[A{{g}^{+}}\]
D.	\[{{I}_{2}}\]
Answer» D. \[{{I}_{2}}\]

Discussion

379.	Given \[E{{{}^\circ }_{C{{u}^{2+}}/Cu}}=0.34V,\,E{{{}^\circ }_{C{{u}^{2+}}/Cu}}=0.15V\] Standard electrode potential for the half cell \[C{{u}^{+}}/Cu\] is
A.	0.38 V
B.	0.53 V
C.	0.19 V
D.	0.49 V
Answer» C. 0.19 V

Discussion

380.	In the electrolysis of \[CuC{{l}_{2}}\] solution, the mass of the cathode increased by 3.2 g. What occured at the copper anode?
A.	0.12 litre of \[C{{l}_{2}}\] was liberated
B.	0.56 litre of \[{{O}_{2}}\] was liberated
C.	0.1 mol \[C{{u}^{2+}}\] passed into the solution.
D.	0.05 mol of \[C{{u}^{2+}}\] passed into the solution.
Answer» E.

Discussion

381.	A solution contains \[F{{e}^{2+}},F{{e}^{3+}}\] and \[{{I}^{-}}\] ions. This solution was treated with iodine at\[35{}^\circ C\]. \[E{}^\circ \] for \[F{{e}^{3+}}/F{{e}^{2+}}\] is + 0.77 V and \[E{}^\circ \] for \[{{I}_{2}}/2{{I}^{-}}=0.536V.\] he favourable redox reaction is:
A.	\[{{I}_{2}}\] will be reduced to \[{{I}^{-}}\]
B.	There will be no redox reaction
C.	\[{{I}^{-}}\] will be oxidised to \[{{I}_{2}}\]
D.	\[F{{e}^{2+}}\] will be oxidised to \[F{{e}^{3+}}\]
Answer» D. \[F{{e}^{2+}}\] will be oxidised to \[F{{e}^{3+}}\]

Discussion

382.	1.08 g of pure silver was converted into silver nitrate and its solution was taken in a beaker. It was electrolysed using platinum cathode and silver anode. 0.01 Faraday of electricity was passed using 0.15 volt above the decomposition potential of silver. The silver content of the beaker after the above shall be
A.	0 g
B.	0.108 g
C.	1.08 g
D.	None of these
Answer» B. 0.108 g

Discussion

383.	\[{{\Lambda }_{ClC{{H}_{2}}COONa}}=224\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}},\]\[{{\Lambda }_{NaCl}}=38.2\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}},\]\[{{\Lambda }_{HCl}}=203\,oh{{m}^{-1}}c{{m}^{2}}ge{{q}^{-1}},\]What is the value of \[{{\Lambda }_{CIC{{H}_{2}}COOH}}\]
A.	\[288.5\,oh{{m}^{-1}}c{{m}^{2}}\,g\,e{{q}^{-1}}\]
B.	\[289.5\,oh{{m}^{-1}}c{{m}^{2}}ge{{q}^{-1}}\]
C.	\[388.8\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]
D.	\[59.5\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]
Answer» D. \[59.5\,oh{{m}^{-1}}c{{m}^{2}}g\,e{{q}^{-1}}\]

Discussion

384.	Resistance of a conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is \[100\Omega .\]. The conductivity of this solution is \[1.29\text{ }S\text{ }{{m}^{-1}}\]. Resistance of the same cell when filled with 0.02 M of the same solution is \[520\Omega \]. The molar conductivity of 0.02 M solution of electrolyte will be
A.	\[1.24\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]
B.	\[12.4\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]
C.	\[124\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]
D.	\[1240\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]
Answer» B. \[12.4\times {{10}^{-4}}\,S{{m}^{2}}mo{{l}^{-1}}\]

Discussion

385.	In the electrolysis of water, one faraday of electrical energy would liberate
A.	one mole of oxygen
B.	one gram atom of oxygen
C.	8 g oxygen
D.	22.4 lit. of oxygen
Answer» D. 22.4 lit. of oxygen

Discussion

386.	A graph was plotted between molar conductivity of various electrolytes \[(NaCl,HCl\,and\,N{{H}_{4}}OH)\] and \[\sqrt{c}(in\,mol\,{{L}^{-1}}).\] Correct set is:
A.	\[I(NaCl),II(HCL),III,(N{{H}_{4}}OH)\]
B.	\[I\left( HCl \right),II\left( NaCl \right),III,\left( N{{H}_{4}}OH \right)\]
C.	\[I\left( N{{H}_{4}}OH \right),II\left( NaCl \right),III,\left( HCl \right)\]
D.	\[I(N{{H}_{4}}OH),II(HCl),III,(NaCl)\]
Answer» C. \[I\left( N{{H}_{4}}OH \right),II\left( NaCl \right),III,\left( HCl \right)\]

Discussion

387.	Thermodynamic efficiency of a cell is given by:
A.	\[\frac{\Delta H}{\Delta G}\]
B.	\[\frac{nFE}{\Delta G}\]
C.	\[\frac{-nFE}{\Delta H}\]
D.	\[nFE{}^\circ \]
Answer» D. \[nFE{}^\circ \]

Discussion

388.	A cell reaction would be spontaneous if the cell potential and \[{{\Delta }_{r}}G\] are respectively:
A.	positive and negative
B.	negative, negative
C.	zero, zero
D.	positive, zero
Answer» B. negative, negative

Discussion

389.	Standard electrode potential for \[S{{n}^{4+}}/S{{n}^{2+}}\] couple is + 0.15 V and that for the \[C{{r}^{3+}}/Cr\] couple is\[-0.74V\]. These two couples in their standard state are connected to make a cell. The cell potential will be:
A.	+1.19 V
B.	+0.89 V
C.	+0.18 V
D.	+1.83 V
Answer» C. +0.18 V

Discussion

390.	1.0 L each of a buffer containing 1 mole \[N{{H}_{3}}\] and 1 mol of \[NH_{4}^{+}\] were placed in the cathodic and anodic half-cells and 965 C of electricity was passed. If anodic and cathodic half cells reactions involve oxidation and reduction of water only as \[2{{H}_{2}}O\xrightarrow{{}}4{{H}^{+}}+{{O}_{2}}-4{{e}^{-}};\] \[2{{H}_{2}}O+2{{e}^{-}}\xrightarrow{{}}{{H}_{2}}+2O{{H}^{-}}\] Then pH of
A.	cathodic solution will increase
B.	anodic solution will decrease
C.	both the solutions will remain practically constant
D.	both the solutions will increase
Answer» D. both the solutions will increase

Discussion

391.	The emf of a particular voltaic cell with the cell reaction \[Hg_{2}^{2+}+{{H}_{2}}\rightleftharpoons 2Hg+2{{H}^{+}}\] is 0.65 V. The maximum electrical work of this cell when 0.5 g of \[{{H}_{2}}\] is consumed.
A.	\[-3.12\times {{10}^{4}}J\]
B.	\[-1.25\times {{10}^{5}}J\]
C.	\[25.0\times {{10}^{6}}J\]
D.	None of these
Answer» B. \[-1.25\times {{10}^{5}}J\]

Discussion

392.	In the silver plating of copper, \[K[Ag{{(CN)}_{2}}]\] is used instead of \[AgN{{O}_{3}}\]. The reason is
A.	a thin layer of Ag is formed on Cu
B.	more voltage is required
C.	\[A{{g}^{+}}\] ions are completely removed from solution
D.	less availability of \[A{{g}^{+}}\] ions, as Cu cannot displace Ag from \[{{[Ag{{\left( CN \right)}_{2}}]}^{-}}\] ion
Answer» E.

Discussion

393.	At 298K the standard free energy of formation of \[{{H}_{2}}O(l)\] is \[-237.20\text{ }kJ/mol\] while that of its ionisation into \[{{H}^{+}}\] ion and hydroxyl ions is 80 kJ/ mol, then the emf of the following cell at 298 K will be [Take Faraday constant F = 96500 C] \[{{H}_{2}}(g,1bar)\|{{H}^{+}}(1M)\|\|O{{H}^{-}}(1M)\|{{O}_{2}}(g,1\,bar)\]
A.	0.40 V
B.	0.81 V
C.	1.23 V
D.	\[-0.40\text{ }V\]
Answer» B. 0.81 V

Discussion

394.	The standard potentials of \[A{{g}^{+}}/Ag,H{{g}_{2}}^{2+}/2Hg,C{{u}^{2+}}/Cu\] and \[M{{g}^{2+}}/Mg\] electrodes are 0.80,0.79, 0.34 and\[-2.37\text{ }V\], respectively. An aqueous solution which contains one mole per litre of the salts of each of the four metals is electrolyzed. With increasing voltage, the correct sequence of deposition of the metals at the cathode is
A.	\[Ag,Hg,Cu,Mg\]
B.	\[Cu,Hg,Ag\] only
C.	\[Ag,Hg,Cu\] only
D.	\[Mg,Cu,Hg,Ag\]
Answer» D. \[Mg,Cu,Hg,Ag\]

Discussion

395.	When electric current is passed through a cell having an electrolytic solution, the cations move towards the cathode and anions towards the anode. If anode is pulled out from the solution
A.	the cations and anions will move towards the cathode
B.	the cations will continue to move towards cathode and anions will stop moving
C.	both the cations and anions will stop moving
D.	the cations and anions will start moving randomly.
Answer» E.

Discussion

396.	A battery is constructed of Cr and \[N{{a}_{2}}C{{r}_{2}}{{O}_{7}}\]. The unbalanced chemical equation when such a battery discharges is following \[N{{a}_{2}}C{{r}_{2}}{{O}_{7}}+Cr+{{H}^{+}}\to C{{r}^{3+}}+{{H}_{2}}O+N{{a}^{+}}\] If one Faraday of electricity is passed through the battery during the charging, the number of moles of \[C{{r}^{\text{3+}}}\] removed from the solution is
A.	\[\frac{4}{3}\]
B.	\[\frac{1}{3}\]
C.	\[\frac{3}{3}\]
D.	\[\frac{2}{3}\]
Answer» D. \[\frac{2}{3}\]

Discussion

397.	A solution of copper sulphate \[\left( CuS{{O}_{4}} \right)\] is electrolysed for 10 minutes with a current of 1.5 amperes. The mass of copper deposited at the cathode (at. mass of\[Cu=63u\]) is:
A.	0.3892 g
B.	0.2938 g
C.	0.2398 g
D.	0.3928 g
Answer» C. 0.2398 g

Discussion

398.	The reduction potential (in volt) of a hydrogen electrode set up with a \[2\times {{10}^{-2}}M\] aqueous solution of a weak mono basic acid \[({{K}_{a}}=5\times {{10}^{-5}})\] at one atmosphere and \[25{}^\circ C\] is
A.	+0.09
B.	0.18
C.	\[-0.09\]
D.	\[-0.18\]
Answer» E.

Discussion

399.	The electrode potential \[{{E}_{(Z{{n}^{2+}}/Zn)}}\] of a zinc electrode at \[25{}^\circ C\] with an aqueous solution of \[0.1\text{ }M\text{ }ZnS{{O}_{4}}\] is\[[E{{{}^\circ }_{(Z{{n}^{2+}}/Zn)}}~=-0.76\text{ }V\]. Assume \[\frac{2.303RT}{F}=0.06\text{ }at\text{ }298\text{ }K].\]
A.	+0.73
B.	\[-0.79\]
C.	\[-0.82\]
D.	\[-0.70\]
Answer» C. \[-0.82\]

Discussion

400.	The e.m.f. of a Daniell cell at 298 K is \[{{E}_{1}}.\]When the concentration of \[ZnS{{O}_{4}}\] is 1.0 M and that of \[CuS{{O}_{4}}\] is 0.01 M, the e.m.f. changed to \[{{E}_{2}}\]. What is the relationship between \[{{E}_{1}}\] and\[{{E}_{2}}\]?
A.	\[{{E}_{2}}=0\ne {{E}_{1}}\]
B.	\[{{E}_{1}}>{{E}_{2}}\]
C.	\[{{E}_{1}}<{{E}_{2}}\]
D.	\[{{E}_{1}}={{E}_{2}}\]
Answer» C. \[{{E}_{1}}<{{E}_{2}}\]

Discussion

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