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When 0.001 M Na2SO4 solution is saturated with CaSO4, its conductivity increases from 2.6 x 10-4 S cm-1 to 7.0 x 10-4 S cm-1. If the molar conductivities of Na+ and Ca2+ respectively are 50 S cm2 mol-1 and 120 S cm2 mol-1, then the solubility product of CaSO4 is: [Assume that conductivity of water used is negligible.]
Conductivity of Na2SO4 = 2.6 x 10-4 S cm-1
The depolariser used in a dry cell battery is
The dry cell contains a conducting solution (electrolyte) of ammonium chloride, a cathode (positive terminal) of carbon, a depolariser of manganese dioxide, and an anode (negative terminal) of zinc.
In a fuel cell, hydrogen gas is oxidised at anode and oxygen is reduced at cathode. If 67.2 L of H2 at STP reacts in 15 minutes, then the average current produced is:
Same amount of electric current is passed through AgNO3 and HCl solutions. If 1.08 g of silver is obtained in the first case, the volume of hydrogen liberated at STP in the second case is
The number of calcium atoms deposited from solution of CaCl2 if 25 milliamperes is passed through it for 60 s is:
During the electrolysis of NaCl, if we use Pt electrode, then H2 is liberated at cathode; while in the presence of Hg cathode, it forms sodium amalgam because
During the electrolysis of NaCl, if we use Pt electrode, then H2 is liberated at cathode; while in the presence of Hg cathode, it forms sodium amalgam because at Hg, more voltage is required to reduce H+ than at Pt electrode.
In the electrolysis of CuSO4 solution, 6.35 g of copper was deposited. If the same amount of electricity is passed through silver nitrate solution, then the mass of Ag deposited at cathode is
The reaction is Cu2+(aq) + 2e– → Cu(s), i.e. 1 mol of Cu is deposited by 2 moles of electrons. For the deposition of 6.35 g Cu (= 0.1 mol Cu), 0.2 mol of electrons will be needed. The deposition of Ag(s) involves the reaction: Ag+(aq) + e– → Ag(s). Thus, for 0.2 mol of electrons, 0.2 mol of Ag will be deposited, which is 0.2 x 108 g, i.e. 21.6 g.
During electrolysis of copper chloride (II) solution, using copper electrodes, the mass of cathode is increased by 3.15 g. Then the reaction taking place at the anode is
The reaction that occurs at the anode is as follows: Cu(s) → Cu+2(aq) + 2e- Thus, 3.15 g of Cu from the anode dissolves and comes into the electrolyte and hence, the mass of the anode decreases.
The most effective method to protect the bottom of a ship made of iron is:
To prevent rusting of iron, it is coated with more reactive white tin because it has lower reduction potential than iron and has greater oxidising power.
The standard reduction potentials of various metals are given as follow: Sn2+/Sn = -0.14 V, Zn2+/Zn = -0.76V, Fe2+/Fe = -0.44 V Pick out the correct statement out of the following:
The lower the reduction potential, the higher is the oxidising power.
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