Chemistry Practice Test – Particulate Nature of Matter (Questions with Answers and Explanations)

If two isotopes of X, mass number 18 and 20 are in ratio 1:2, then the relative atomic mass of X is _____

A. 18.33    B. 18.61    C. 19.00    D. 19.33

The elements A, has atomic numbers 11. The formula of the electronic configurations of A is _____ 

A. 1s² 2s² 2p⁴        B. 1s² 2s² 2p⁶ 3s¹       C. 1s² 2s² 2p⁶ 3s²      D. none of the above

How many atoms are there in one mole of hydrogen gas? [Avogadro’s constant = 6.02 x 10²³ mol-1] (WASSCE 2007)

A. 1.2 x 10²³       B. 6.0 x 10²³      C. 12 x 10²⁴     D. 60 x 10²⁴