(a) It is certain to happen. Because, the sum of angles of a triangle as 180o.
(b) It may or may not happen. Because, the result of match is unpredictable.
(c) It is certain to happen. Because, the sun always sets in the evening.
(d) It is impossible to happen. Because, 7 is not an outcome when a dice is thrown.
(e) It is impossible to happen. Because, Sun always rises from the east.
(f) It may or may not happen. Because, the result is unpredictable.