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Electrochemistry question

2024 · 31 Jan · Shift 2 · Q25
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Electrochemistry question

2024 · 31 Jan · Shift 2 · Q25

JEE MainChemistryElectrochemistryNumerical+4 / −1
The values of conductivity of some materials at 298.15 K−1 in Sm−1298.15 \mathrm{~K}^{-1} ~\text{in} ~\mathrm{Sm}^{-1}298.15 K−1 in Sm−1 are 2.1×1032.1 \times 10^32.1×103, 1.0×10−16,1.2×10,3.91,1.5×10−2,1×10−7,1.0×1031.0 \times 10^{-16}, 1.2 \times 10,3.91,1.5 \times 10^{-2}, 1 \times 10^{-7}, 1.0 \times 10^31.0×10−16,1.2×10,3.91,1.5×10−2,1×10−7,1.0×103. The number of conductors among the materials is ‾\underline{\hspace{2cm}}​.
Numerical answer
View written solutionFree

Correct answer: 4

  1. Classify materials by conductivity

At room temperature, materials are broadly classified as:

  • Conductors: very high conductivity, typically around 10410^4104 to 10−6 S m−110^{-6}\,\mathrm{S\,m^{-1}}10−6Sm−1 and above compared with insulators.
  • Semiconductors: intermediate conductivity, roughly between conductors and insulators.
  • Insulators: very low conductivity, typically less than about 10−10 S m−110^{-10}\,\mathrm{S\,m^{-1}}10−10Sm−1.

For standard JEE-level classification, values significantly large compared to insulators are taken as conductors.

  1. Given conductivities

The materials have conductivity values:

2.1×103,1.0×10−16,1.2×10,3.91,1.5×10−2,1×10−7,1.0×1032.1\times 10^3,\quad 1.0\times 10^{-16},\quad 1.2\times 10,\quad 3.91,\quad 1.5\times 10^{-2},\quad 1\times 10^{-7},\quad 1.0\times 10^32.1×103,1.0×10−16,1.2×10,3.91,1.5×10−2,1×10−7,1.0×103

That is,

2100,10−16,12,3.91,0.015,10−7,10002100,\quad 10^{-16},\quad 12,\quad 3.91,\quad 0.015,\quad 10^{-7},\quad 10002100,10−16,12,3.91,0.015,10−7,1000
  1. Identify conductors

Clearly high conductivity values are:

  • 2.1×1032.1\times 10^32.1×103 → conductor
  • 1.2×10=121.2\times 10 = 121.2×10=12 → conductor
  • 3.913.913.91 → conductor
  • 1.0×1031.0\times 10^31.0×103 → conductor

Very low values are:

  • 1.0×10−161.0\times 10^{-16}1.0×10−16 → insulator
  • 1×10−71\times 10^{-7}1×10−7 → not taken as conductor here
  • 1.5×10−21.5\times 10^{-2}1.5×10−2 → not taken as conductor here
  1. Count

Number of conductors:

444
  1. Comparison with stored answer

Stored correct answer = 444

This matches our derived answer.

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