Q. 50

# Match the terms given in Column I with the units given in Column II.

Answer :

(i) Λ_{m} → (c) S cm^{2} mol^{-1}

Here, Λ_{m} represents the molar conductivity.

Molar conductivity is expressed as Conductivity of the solution divided by its concentration.

Thus,

Λ_{m} = = = S cm^{2} mol^{-1}

(ii) E_{cell} → (d) V

Here, E_{cell} represents the emf (electromotive force) of the cell and is expressed as the difference of the potential of the two half cells i.e., cathode and anode. Thus, the unit of E_{cell} is equalto ‘Volt’ and is denoted as ‘V’.

(iii) κ → (a) S cm^{-1}

Here, κ (kappa) denotes the conductivity or the specific conductance of the cell.

We know, Resistance (R) = ρ =

Or, κ = G = = S cm^{-1}

Where, ρ = Resistivity or specific resistance =

L= Distance between the electrodes = length

A= Area of cross section of the electrode

G= = Conductance

S= Siemens= SI unit of conductance

(iv) G^{*} → (b) m^{-1}

Here, G^{*} represents the cell constant.

We know, G^{*} =

Or, G^{*}= Conductivity x Resistance = x Ω

= S m^{-1} x S^{-1} (Since, Ω = S^{-1})

= m^{-1}

Where, Ω is the SI unit of resistance.

Rate this question :

Match the items of Column I and Column II.

Assertion : Conductivity of all electrolytes decreases on dilution.

Reason : On dilution number of ions per unit volume decreases.

Chemistry - Exemplar