JAMB Chemistry Past Questions & Answers - Page 423

\(_{22}X^{2+}\) has 22 electrons but has been ionized to 2+ by giving off 2 electrons. Hence, the ion \(_{22}X^{2+}\) has 20 electrons.

The electronic configuration = 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^6\) 3d\(^2\) 

the general trend for the first-row transition metals is that they lose electrons from their 4s orbitals first before 3d when forming ions. but this is not true for chromium and copper due to stability related to half-filled or completely-filled 3d orbitals

The valence electron of the elements in the same period increase progressively across the period due to an increase in atomic number

the fundamental difference between the three states of matter is their degree of movement, gaseous particles are very loosely packed hence they can move about easily. The particles of solids are closely packed so solids only make vibrational movement, while liquid particles can move past each other because their particles are not as closely packed as those of solids. 

Mole fraction = \(\frac{\text{Partial pressure of component}}{\text{Total pressure of compound}}\)

= \(\frac{452}{780}\)

= 0.579

From P₁V₁ = P₂V₂
1 * V₁ = 1.5 * V₂
((1 * 300)/1.5) = V₂
∴ V₂ = 200 cm³