Question 3 - MCQs from (Past Year Papers & NCERT Exemplar) - Chapter 5 Class 10 - Periodic Classification of Elements

Consider the following statements about an element ‘X’ with number of protons 13. 

(A) It forms amphoteric oxide.

(B) Its valency is three.

(C) The formula of its chloride is XCl.

The correct statements(s) is/are:

(a) only (A)

(b) only (B)

(c) (A) and (C)

(d) (A), (B) and (C)

Answer

Number of protons in X = Number of electrons in X = 13

Thus, 

Electronic configuration of X= 2, 8, 3

The element with the electronic configuration given above is Aluminium.

Checking the options:

• (A) It forms amphoteric oxide - Aluminium oxide is an amphoteric oxide. So, this is true.
• (B) Its valency is three - The number of electrons in the outermost shell is 3. So, this is true.
• (C) The formula of its chloride is XCl - The formula of aluminium chloride is AlCl 3 . So, this is not true.

Therefore, the correct options are (A) and (B)