Resistance and Resistivity

Q. Resistivity is independent of

1. length of the material
2. Cross section area of the material
3. Nature of the material
4. both (a) and (b)

Q.

Which of the following wires, all made of the same material has the highest resistance

1. $L=100cm,r=0.1cm$

2. $L=200cm,r=0.2cm$

3. $L=300cm,r=0.3cm$

4. $L=400cm,r=0.4cm$

Q. The resistance of a $0.02N$ solution of an electrolyte $MgC{l}_2$ was found to be $210ohm$ at $298K$ using a conductivity cell with a cell constant of $0.88c{m}^{-1}$. Calculate the equivalent conductivity of the solution.

1. $625oh{m}^{-1}c{m}^{2}e{q}^{-1}$
2. $500oh{m}^{-1}c{m}^{2}e{q}^{-1}$
3. $209.5oh{m}^{-1}c{m}^{2}e{q}^{-1}$
4. $125.5oh{m}^{-1}c{m}^{2}e{q}^{-1}$

Q. Resistance is reciprocal of conductance. True or false?

1. True
2. False

Q. A $0.1M$ solution of a monobasic acid has a specific resistance of ‘r’ Ωcm, its molar conductivity is:

1. 10/r
2. 10 r
3. ${10}^4/r$
4. ${10}^4$ r

Q. The resistance of a $0.02N$ solution of an electrolyte $MgC{l}_2$ was found to be $210ohm$ at $298K$ using a conductivity cell with a cell constant of $0.88c{m}^{-1}$. Calculate the equivalent conductivity of the solution.

1. $209.5oh{m}^{-1}c{m}^{2}e{q}^{-1}$
2. $125.5oh{m}^{-1}c{m}^{2}e{q}^{-1}$
3. $625oh{m}^{-1}c{m}^{2}e{q}^{-1}$
4. $500oh{m}^{-1}c{m}^{2}e{q}^{-1}$

Q. Rajat, Sarath and Komal decided to measure resistance of aluminium and took bars of aluminium separately and measured its resistance in same room but got different values of resistance, of same material aluminium. What can be the probable reasons for these variations in resistance for same material?

1. they took bars of same length but different cross section area
2. they took bars of same cross section area but different length.
3. both length and cross section area of bars were different
4. All of the above

Q. The conductivity of $0.1MNaCl$ is $3\times {10}^{-3}Sc{m}^{-1}$ and its resistance in an electrolytic cell is $500ohm$. Resistance of $\frac{1}{20}MCuS{O}_4$ solution measured in the same cell at the same temperature is found to be $70ohm$. The molar conductivity of the given $CuS{O}_4$ solution is ?

1. $20.5Sc{m}^{2}mo{l}^{-1}$
   
2. $428Sc{m}^{2}mo{l}^{-1}$
   
3. $12.50Sc{m}^{2}mo{l}^{-1}$
   
4. $120.2Sc{m}^{2}mo{l}^{-1}$
   

Q. Assertion: Oxidation state of hydrogen is +1 in $H_{2}O$ while -1 in $Ca{H}_2$.
Reason: $Ca{H}_2$ is a metal hydride and for hydrides, hydrogen is assigned the oxidation number of -1.

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> AIIMS 2018

1. Both Assertion and Reason are false.
2. Both Assertion and Reason are true and Reason is the correct explanation for Assertion.
3. Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.
4. Assertion is true but Reason is false.

Q. $1.0N$ solution of a salt surrounding two platinum electrodes of $2.1cm$ apart and $4.2c{m}^2$ in area was found to offer a resistance of $50ohm$. Calculate the equivalent conductivity of the solution.

1. ${\Lambda }_{eq}=0.01oh{m}^{-1}c{m}^{2}e{q}^{-1}$
2. ${\Lambda }_{eq}=10oh{m}^{-1}c{m}^{2}e{q}^{-1}$
3. ${\Lambda }_{eq}={10}^{-5}oh{m}^{-1}c{m}^{2}e{q}^{-1}$
4. ${\Lambda }_{eq}=100oh{m}^{-1}c{m}^{2}e{q}^{-1}$