Question

Falak lists the four events involved in the formation of sinkholes.

W - Acidic rainwater dissolves the limestone bedrock.
X - Large cavities form in the bedrock.
Y - Natural holes and cracks become bigger.
Z - The ceiling collapses due to the weight of sediment.

Which list shows the correct order of these events in the formation of sink holes?

W, X, Y, Z
W, Y, X, Z
W, Z, Y, X
W, Z, X, Y

Answer 1

W, Y, X, Z

Reason: Acidic rainwater first dissolves the limestone (W). That makes natural cracks and holes enlarge (Y), which over time merge into large cavities (X). Eventually the roof of a cavity can no longer support the overlying sediment and collapses (Z).