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# An Element X Belongs to Group 2 and Another Element Y Belongs to Group 15 of the Periodic Table: (A) What is the Number of Valence Electron in X? (B) What is the Valency of X? (C) What is the Number of Valence Electrons in Y? (D) What is the Valency of Y? Explain How You Have Arrived at Your Answers. - CBSE Class 10 - Science

ConceptPosition of Elements and Trends in the Modern Periodic Table

#### Question

An element X belongs to group 2 and another element Y belongs to group 15 of the periodic table:

(a) What is the number of valence electron in X?
(b) What is the valency of X?
(c) What is the number of valence electrons in Y?
(d) What is the valency of Y?

#### Solution

(a) The number of valence electrons in element X is 2 because this element belongs to group 2.

(b) The valency of the group 2 element X is 2.

(c) Valence electrons of group 15:
Group number = Valence electrons + 10
15 = Valence electrons + 10
Valence electrons = 15 - 10 = 5

(d) Valency of the group 15 element Y is 3, that is, (8 - 5).

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#### APPEARS IN

Lakhmir Singh Solution for Chemistry for Class 10 (2019 Exam) (2018 to Current)
Chapter 5: Periodic Classification Of Elements
Q: 22 | Page no. 303

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Solution An Element X Belongs to Group 2 and Another Element Y Belongs to Group 15 of the Periodic Table: (A) What is the Number of Valence Electron in X? (B) What is the Valency of X? (C) What is the Number of Valence Electrons in Y? (D) What is the Valency of Y? Explain How You Have Arrived at Your Answers. Concept: Position of Elements and Trends in the Modern Periodic Table.
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