Assertion- The atomic weight of an element is given by Dulong Petit-s law -Atomic weight - specific heat cal -mole - 6-4Reason- The formula is valid for metals only and not for all elements-

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Standard IX

Chemistry

Molecules and Atomicity

Assertion: Th...

Question

Assertion: The atomic weight of an element is given by Dulong Petit's law :
Atomic weight $\times$ specific heat (cal /mole) = 6.4

Reason: The formula is valid for metals only and not for all elements.

Assertion is correct but Reason is wrong.

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Assertion is wrong but Reason is correct.

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both Assertion and Reason are correct and Reason is the correct explanation of Assertion

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both Assertion and Reason are correct but Reason is not the correct explanation of Assertion

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Solution

The correct option is A Assertion is correct but Reason is wrong.
The correct expression for Dulong Petit's law is "molar mass (M) (g/mol) $\times$ specific heat (c) (J/g.K) $=$ 25 J/mol. K".
This equation is valid for metals and solids elements having an atomic mass more than 40 and not for all elements.
Hence, Assertion is correct but Reasoning is wrong.

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Assertion: The atomic weight of an element is given by Dulong Petit's law :Atomic weight × specific heat (cal /mole) = 6.4Reason: The formula is valid for metals only and not for all elements.

Assertion: The atomic weight of an element is given by Dulong Petit's law :
Atomic weight $\times$ specific heat (cal /mole) = 6.4

Reason: The formula is valid for metals only and not for all elements.