QUESTION 2 (a) Imperfection refers to deviations in the regular pattern of crystalline lattice structure. (i) Sketch and label a vacancy, an interstitial atom and a substitutional atom which represent imperfections in a metal lattice in one diagram. [3 marks] (ii) Explain why impurity atoms of substitutional or interstitial type of point defects are sometimes intentionally added to certain materials. [2 marks] (a) Imperfection refers to deviations in the regular pattern of crystalline lattice structure. (i) Sketch and label a vacancy, an interstitial atom and a substitutional atom which represent imperfections in a metal lattice in one diagram. [3 marks] (ii) Explain why impurity atoms of substitutional or interstitial type of point defects are sometimes intentionally added to certain materials. [2 marks]