Question

47. All elements present in the same group have...
Same valency
Different valency
Valency in increasing order
Valency in decreasing order​

Answer 1

Explanation:

All elements present in the same group have a) Same valency.

Valency of an element determines its chemical reactivity.Therefore, for all elements belonging to a particular group in the periodic table, the number of electrons in the outermost shell, that is the valence electrons will be the same.

Hence, all the elem in that group will show the same chemical reactivity. They will react with different elements in the same way and the molecular formula of their compounds will be similar. Hence, they have the same chemical properties.

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Answer 2

Answer :

All elements present in the same group have similar valence shell electronic configuration, therefore, exhibit similar chemical properties $.$

Hence, (A) is the correct answer!

Additional Information :

• The recurrence of similar properties of the elements after certain definite intervals when the elements are arranged in order of increasing atomic numbers in the periodic table is called periodicity.
• The cause of periodicity is the repetition of similar electronic configuration of the atom in the valence shell after certain definite intervals. These definite intervals are 2, 8, 8, 18, 18 and 32.
• Periodicity is observed in a number of properties which are directly or indirectly linked with electronic configuration.

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