Question

An element X has 7 electrons in its L shell. What is true about the element X ?
I. It belongs to period 9 of modern periodic table.
II. Its atom contains 9 protons.
III. It has a valency of 1.
IV. Its atoms can accept an electron to acquire noble gas configuration.

• A. (I) and (II)
• B. (II), (III), (IV)
• C. (III) and (IV)
• D. (II) and (IV)

Answer 1

Answer: (B)

(II), (III), (IV)

Given, no. of electrons in L shell =7
Hence, no. of protons = 2 + 7 = 9
Electronic configuration = 2, 7
To complete octet, element requires one e${}^{-}$. Hence, valency will be one.