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question_answer1) The blue colour of copper sulphate solution is discharged when a rod of zinc is dipped in it. Explain.
question_answer2) Why cannot oxidation occur without reduction?
question_answer3) Articles of iron are generally coated with zinc. Explain.
question_answer4) Why is anode negatively charged in an electrochemical cell?
question_answer5) Why is standard hydrogen electrode called reversible electrode?
question_answer6) Check the feasibility of the following redox reaction with the help of electrochemical series \[Ni(s)+2A{{g}^{+}}(aq)\,\xrightarrow{\,}N{{i}^{2+}}(aq)+2Ag(s)\]
question_answer7) What will happen when chlorine is passed through an aqueous solution of potassium bromide?
question_answer8) What is the source of electrical energy in a galvanic cell?
question_answer9) Knowing that: \[C{{u}^{2+}}(aq)+2{{e}^{-}}\xrightarrow{\,}\,Cu(s);\]\[{{E}^{0}}=+0.34\,\text{V}\] \[2A{{g}^{+}}\,(aq)+2{{e}^{-}}\xrightarrow{{}}2Ag\,(s);\,\,\,E{}^\circ =+0.80\,V\] reason out whether, 1M silver nitrate solution can be stored in copper vessel or 1M copper sulphate solution in silver vessel.
question_answer10) Determine the oxidation number of the element in the bold in the following species (i)\[Si{{H}_{4}}\] (ii)\[B{{H}_{3}}\] (iii)\[B{{F}_{3}}\] (iv)\[{{S}_{2}}O{{_{3}^{{}}}^{2-}}\] (v)\[BrO{{_{4}^{{}}}^{-}}\] (vi)\[HP{{O}_{4}}^{2-}\]
question_answer11) Identify the oxidants and reductants in the following reactions (a)\[C{{H}_{4}}(g)+4C{{l}_{2}}(g)\xrightarrow{\,}\,CC{{l}_{4}}(g)+4HCl\,(g)\] (b)\[2{{H}^{+}}\,(aq)+Mn{{O}_{2}}\,(s)+{{C}_{2}}{{H}_{2}}{{O}_{4}}\,(aq)\xrightarrow{{}}M{{n}^{2+}}\,(aq)+2C{{O}_{2}}\,(g)+2{{H}_{2}}O\,(l)\] (c) \[{{I}_{2}}(aq)+2{{S}_{2}}{{O}_{3}}^{2-}\,(aq)\xrightarrow{\,}2{{I}^{-}}(aq)\]\[+{{S}_{4}}{{O}_{6}}^{2-}(aq)\] (d)\[C{{l}_{2}}(g)+2\,B{{r}^{-}}\,(aq)\xrightarrow{{}}2C{{l}^{-}}\,(aq)+B{{r}_{2}}\,(aq)\]
question_answer12) Write the O.N. of all the atoms in the following well known oxidants: (i)\[KMn{{O}_{4}}\] (ii)\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] (iii)\[KCl{{O}_{4}}\]
question_answer13) What is oxidation according to electronic concept?
question_answer14) Define reducing agent.
question_answer15) Arrange the following in order of increasing O.N. of iodine: \[{{I}_{2}},\,HI,\,HI{{O}_{2}},\,KI{{O}_{3}},\,ICl\]
question_answer16) What is the oxidation number of hydrogen in \[LiAl{{H}_{4}}\]? Name a compound in which hydrogen has the same oxidation state.
question_answer17) \[{{H}_{2}}{{O}_{2}}\] changes to \[{{O}_{2}}\]. What is the change in oxidation number of oxygen per atom?
question_answer18) What is O.N. of carbon in \[{{(CN)}^{-}}\]ion?
question_answer19) Which is the anhydride of \[HN{{O}_{3}}\] out of \[{{N}_{2}}O,\,NO\] and \[{{N}_{2}}{{O}_{5}}\]?
question_answer20) Out of \[{{(HS{{O}_{4}})}^{-}}\]and \[{{(HS{{O}_{3}})}^{-}}\] which is a stronger base?
question_answer21) Identify the oxidant and reductant in the following redox reaction: \[2{{K}_{2}}Mn{{O}_{4}}+C{{l}_{2}}\xrightarrow{\,}\,2KCl+2KMn{{O}_{4}}\]
question_answer22) Give one example of disproportionation reaction \[2{{H}_{3}}\overset{+1}{\mathop{P}}\,{{O}_{2}}\,\xrightarrow{heat}\,\overset{-3}{\mathop{P}}\,{{H}_{3}}+{{H}_{3}}\overset{+5}{\mathop{P}}\,{{O}_{4}}\]
question_answer23) What is the oxidation state of sodium in sodium amalgam (Na/Hg)?
question_answer24) What is the oxidation number of chlorine in bleaching powder?
question_answer25) Is the following reaction a redox reaction is nature? Justify your answer. \[C{{r}_{2}}O_{7}^{2-}\,+{{H}_{2}}O\xrightarrow{\,}\,2CrO_{4}^{2-}\,+2{{H}^{+}}\]
question_answer26) Is it safe to stir \[1\,M\,AgN{{O}_{3}}\] solution with copper spoon? Given:\[E{}^\circ A{{g}^{+}}/Ag=0.80\,V;\] \[{{E}^{o}}\,C{{u}^{2+}}/Cu=0.34\,\text{V}\].
question_answer27) Balance the following redox equation in acidic medium \[Cu+N{{O}_{3}}^{-}\to N{{O}_{2}}+C{{u}^{2+}}\]
question_answer28) (a) Define oxidation. (b) Which is the O.N of sulphur in \[{{H}_{2}}S\] and of carbon in \[{{C}_{6}}{{H}_{12}}{{O}_{6}}\]?
question_answer29) Define reducing agent.
question_answer30) What are the maximum and minimum oxidation numbers of N, S and Cl?
question_answer31) Nitric acid acts only as an oxidising agent while nitrous acid acts both as an oxidising as well as a reducing agent. Why?
question_answer32) Can the reaction, \[C{{r}_{2}}O_{7}^{2-}+{{H}_{2}}O\,\,\,\rightleftarrows \,2CrO_{4}^{2-}+2{{H}^{+}}\] be regarded as a redox reaction?
question_answer33) Write the following redox reactions using half equations. (i) \[Zn(s)+PbC{{l}_{2}}(aq)\xrightarrow{\,}\,Pb(s)+ZnC{{l}_{2}}(aq)\] (ii)\[2F{{e}^{3+}}(aq)+2{{I}^{-}}(aq)\,\xrightarrow{\,}\,{{I}_{2}}(s)+2F{{e}^{2+}}(aq)\] (iii) \[2Na(s)+C{{l}_{2}}(g)\xrightarrow{\,}\,2NaCl\,(s)\] (iv)\[Mg(s)+C{{l}_{2}}(g)\xrightarrow{\,}\,MgC{{l}_{2}}(s)\] (v) \[Zn(s)+2{{H}^{+}}(aq)\xrightarrow{{}}\,Z{{n}^{2+}}(aq)+{{H}_{2}}(g)\] In each of the reactions given above, mention (a) which reactant is oxidized? To what? (b) which reactant is the oxidiser? (c) which reactant is reduced? To what? (d) which reactant is the reducer?
question_answer34) The standard electrode potentials at 298 K are given below: \[E{{{}^\circ }_{Z{{n}^{2+}}/Zn}}=-0.76\,V,\]\[E{{{}^\circ }_{F{{e}^{2+}}/Fe}}=-0.44\,V,\]\[E{{{}^\circ }_{{{H}^{+}}/{{H}_{2}}}}=0.0\,V\] and\[{{E}^{{}^\circ }}_{C{{u}^{2+}}/Cu}=+0.34V.\] Which of the two electrodes should be combined to form a cell having highest EMF? Identify the cathode and the anode and write the cell reaction. Also mention the direction of flow of electrons in the external as well as the internal circuit.
question_answer35) An iron rod is immersed in a solution containing \[1.0\,M\,NiS{{O}_{4}}\] and \[1.0\,M\,ZnS{{O}_{4}}\] . Predict giving reasons which of the following reactions is likely to proceed? (i) Fe reduces \[Z{{n}^{2+}}\] ions, (ii) Iron reduces \[N{{i}^{2+}}\] ions. Given: \[E{{{}^\circ }_{Z{{n}^{2+}}/Zn}}=-0.76\,V,\]\[E{{{}^\circ }_{F{{e}^{2+}}/Fe}}=-0.44\,V\] \[and\,\,\,{{E}^{{}^\circ }}_{N{{i}^{2+}}/Ni}=-0.25V\]
question_answer36) The electrode potential of four metallic elements (A, B, C and D) are + 0.80, -0.76, +0.12 and +0.34 V respectively. Arrange them in order of decreasing electropositive character.
question_answer37) \[{{I}_{2}}\]and\[B{{r}_{2}}\] are added to a solution containing \[B{{r}^{-}}\] and \[{{I}^{-}}\] ions. What reaction will occur if, \[{{I}_{2}}+2{{e}^{-}}\xrightarrow{}2{{I}^{-}};{{E}^{{}^\circ }}=+0.54V\,and\]\[B{{r}_{2}}+2{{e}^{-}}\xrightarrow{}2B{{r}^{-}};{{E}^{{}^\circ }}=+1.09V?\]
question_answer38) Is it possible to store: (i) Copper sulphate solution in a zinc vessel? (ii) Copper sulphate solution in a silver vessel? (iii) Copper sulphate solution in a gold vessel? Given: \[E{{{}^\circ }_{C{{u}^{2+}},\,Cu}}=+0.34\,V;\]\[E{{{}^\circ }_{A{{g}^{+}},\,Ag}}=+0.80\,V\] and\[E{}^\circ {{\,}_{A{{u}^{3+}},\,Au}}=+\,1.50\,V\].
question_answer39) How does \[C{{u}_{2}}O\] act as both oxidant and reductant? Explain with proper reactions showing the change of oxidation numbers in each example.
question_answer40) What is the name of the reaction, \[2\,C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}SH\xrightarrow{\,}\,C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}\]\[-S-S-C{{H}_{2}}C{{H}_{2}}C{{H}_{3}}\] (Whether condensation, oxidation, reduction or polymerization)
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