Periodic Classification Of Elements PYQs — 4 UPSC CSE Previous Year Questions

Question 1

Consider the following statements : Statement I : Some rare earth elements are used in the manufacture of flat television screens and computer monitors. Statement II : Some rare earth elements have phosphorescent properties. Which one of the following is correct in respect of the above statements?

Accepted Answer

A. Both Statement I and Statement II are correct and Statement II explains Statement I

Question 2

Which one of the following is also called Stranger Gas?

Accepted Answer

C. Xenon

Question 3

Assertion (a) : In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group Reason (R): In a group, the atomic radii generally increase from top to bottom.

Accepted Answer

D. A is false but R is true

Question 4

Consider the following statements with reference to the periodic table of chemical elements:

lonisation potential gradually decreases 'along a period.
In a group of elements, electron affinity decreases as the atomic weight increases.
In a given period, electronegativity decreases as the atomic number increases.

Which of these statements(s) is/are correct?'

Accepted Answer

B. 2 only