Question

Choose the correct option

(a) Rutherford's alpha-particle scattering experiment discovered

A. Electron B. Proton

C. Atomic nucleus D. Neutron

(b) Number of valence electrons in $O^{2-}$ is :

A. 6 B. 8

C. 10 D. 4

(c) Which of the following is the correct electronic configuration of potassium ?

A. 2, 8, 9 B. 8, 2, 9

C. 2, 8, 8, 1 D. 1, 2, 8, 8

Answer 1

a). The correct answer choice is C. Atomic nucleus

b) The correct answer choice B. 8

The number of valence electrons in the $O^{2-}$ ion is 8. Oxygen (atomic number 16) has6 electrons in the outermost shell. O^2- has 2 more electrons. Thus, in total there are 8 electrons.

c) The correct answer choice C. 2, 8, 8, 1

Potassium (K) = The atomic number is 19. Its electronic configuration is (2,8,8,1).