Question

ASSERTION: The atomic mass of phosphorus is 31 and its molecular mass is 62.
REASON: Atomicity of phosphorus is 4.
a) both assertion and reason are correct statements and reason is the correct explanation of the assertion.
b)Both assertion and reason are correct statement, reason is not the correct explanation of the assertion.
c) Assertion is correct statement, but reason is incorrect statement.
d) assertion is incorrect statement but, reason is correct statement. ​

Answer 1

Answer:

option -A is the right answer

Explanation:

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Answer 2

Given:

ASSERTION : The atomic mass of phosphorus is 31 and its molecular mass is 62.

REASON : Atomicity of phosphorus is 4.

We know that:

• Phosphorous is an element which is represented in the Periodic Table as ₁₅P³¹ .

• Thus, it has atomic mass equal to 31.

• Phosphorous is a tetra-atomic element.
• Thus, it has atomicity of 4 (tetra = 4)
• So, its molecular formula is P₄

Molecular mass:

Molecular mass of molecule = (Atomic mass) * Atomicity

=> So, molecular mass of P₄ = 31 * 4 => 124 .

To the question:

=> Atomic mass of Phosphorous is 32 but molecular mass is not 62 but 124. (Contradictory to Assertion)

=> Atomicity of Phosphorous is indeed 4. (Supporting the Reason)

=> So, the Assertion is incorrect but Reason is correct statement.

So, the correct answer is (d) Assertion is incorrect but reason is correct statement.

More to know:

=> Atomicity of some other molecules.

》Sulphur - 8 (Octa-atomic) - Molecular formula = S₈

》Oxygen - 2 (Diatomic gas) - Molecular formula = O₂

》Argon - 1 (Monoatomic inert gas) - Molecular formula = Ar

》Chlorine (& all other halogens) (Diatomic) - Cl₂