Chemistry
Assertion (A): Second period consists of 8 elements.
Reason (R): Number of elements in each period is four times the number of atomic orbitals available in energy level that is being filled.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Periodic Table
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Answer
A is true but R is false.
Explanation — The second period includes the elements from lithium (Z=3) to neon (Z=10): Li, Be, B, C, N, O, F, Ne → 8 elements. Hence assertion is true. Reason given is incorrect. In the first period, electrons are being added to the K electronic configuration.
The number of available electronic configuration or orbital for elements of first period is 1.
The number of elements present in the first period is 2, which is not four times the number of atomic orbitals available. Hence the (R) statement is false.
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Related Questions
Element 'P' has electronic configuration 2,8,8,1. The number of chlorine atoms present in the chloride of 'P' is:
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Which of the following electronic configuration represents the most electropositive element?
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Assertion (A): In a Dobereiner's triad, the three elements present have the same difference of atomic masses.
Reason (R): Elements in a triad have similar properties.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
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Assertion (A): Smaller the size of an atom greater is its electronegativity.
Reason (R): Electronegativity is the tendency of an atom to attract shared pair of electrons towards itself in a molecule.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.