ECAT Chemistry Online Test With Answers

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ECAT Chemistry Online Test

Sr. # Questions Answers Choice
1 Reversible reaction Irreversible reaction Spontaneous reaction None of these
2 When rate of forward reaction is equal to rate of backward reaction, then the equilibrium established is called Chemical equilibrium Static equilibrium Dynamic equilibrium None of these
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5 The rate of which the reaction proceeds is directly proportional to the product of the active masses of the reactants is according to Law of mass action Le Chateliers principle Equilibrium law Law of constant proportion
6 At equilibrium there is no further change in the concentration of Hl At equilibrium concentration of l<sub>2</sub>remains constant At equilibrium concentration of H<sub>2</sub>remains unaltered At equilibrium the rate of formation of Hl is equal to the rate of decomposition of Hl
7 Which of the following in an example of reversible reaction
8 Li has the lowest reduction potential while the element with highest reduction potential is H F O N
9 Which statement is incorrect for balancing of redox reactions by ion-electron method The reaction is splitted into two half reactions H<sub>2</sub>O and H<sup>+</sup>ions are added for acidic or neutral reaction to balance O and H atoms To balance H, HCi, is added To balance O and H in the alkaline reaction OH<sup>-</sup>added
10 Metals like Fe, Mg, Al, Cr, Zn have more negative reduction potentials that is whey These don't react with steam These react very slowly with steam to liberate H<sub>2</sub>gas These react rapidly with steam to produce the metallic oxides and liberate H<sub>2</sub>gas These react with cold water violently
11 Coinage metals like Au, Pt, Ag and Cu are the least reactive metals and don't liberate H2gas when treated with acids because These have very high positive values of reduction potentials These have very high negative values of reduction potentials Their ionization potentials are lowest Their reduction potentials are close to SHE
12 Metals which are above SHE in electrochemical series Can liberate H<sub>2</sub>from acid Cannot liberate H<sub>2</sub>from acid Cannot always liberate H<sub>2</sub>from acid None of these
13 Cu H N O
14 Strong reducing agents gave Greater positive value of standard reduction potential Greater negative value of standard reduction potential Lesser positive value of standard reaction potential None of these
15 In a compound an atom has negative oxidation state because Atom is negatively charged Atom acts as cathode Atom is more electronegative Atom has lowest ionization energy
16 The oxidation number of chromium in K2Cr2O7is 14 12 6 None of these
17 The oxidation state of an element is zero when It forms an oxide It forms hydride It is in free state Only for noble gases
18 The oxidation number of Mn is KMnO4is +2 +4 +6 +7
19 Oxidation number of oxygen in OF2is +1 -1 +2 -2
20 The oxidation number of H is -1 in the compound H<sub>2</sub>O H<sub>3</sub>BO<sub>3</sub> NaOH NaH
21 Which statement is correct for the fuel cells These cells operate at low temperature These cells operate at low temperature No catalyst used for the formation of water MnO<sub>2</sub>is used as electrolyte
22 Which statement is incorrect for NICAD battery The electrolyte is alkali Cd acts as anode MnO<sub>2</sub>acts as electrolyte NiO<sub>2</sub>acts as cathode
23 Lead accumulator stops discharging current when Lead at anode converted to PbO<sub>2</sub> PbO<sub>2</sub>at cathode converted to Pb Both electrodes are completely covered with PbSO<sub>4</sub> Both electrodes are completely covered with Pb(OH)<sub>2</sub>
24 Silver oxide battery has a voltage of 2.0 V 1.5 V 2.5 V 1.0 V
25 During electrolysis of KNO3, H2is evolved Anode Cathode Both a and b None
26 In electronic watches or electronic calculators the tiny batteries used are Alkaline battery NICAD battery Fuel cell Silver oxide battery
27 A dry alkaline cell has porous Zn anode and MnO2as cathode the electrolyte used is Ca(OH)<sub>2</sub> NaOH KOH NH<sub>4</sub>OH
28 Fe is reduced Fe is oxidized Cl<sub>2</sub>is oxidized None of these
29 Alkaline battery has a voltage of 4.5 V 3.5 V 2.5 V 1.5 V
30 Which one of the following reactions is not spontaneous
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