A road tanker carrying an acid was involved in an accident, and its content spilled on the road. At the side of the road, iron drain covers began melting and fizzing as the acid ran over them. A specialist was called to see if the acid actually leaked into the nearby river. (a) Explain how the specialist could carry out a simple test to see if the river water contains some acid or not. (b) The word "melting" is incorrectly used in the report. Suggest a better name that should have been used for the same purpose. (c) Explain why drain covers began fizzing as the acid ran over them.

(a) To see if the river water contains some acid or not, the specialist can use a blue litmus paper. If the blue litmus paper changes to red, then it is confirmed that the river contains some acid and if the colour does not change, this means river does not contain any acid.

(b) Corroding is the right term instead of melting. Hence, the correct sentence is “At the side of the road, iron drain covers began corroding and fizzing as the acid ran over them.”

(c) Iron drain covers began fizzing because when acid ran over them reacts with iron; it releases hydrogen gas. Due to the formation of hydrogen gas, bubbles occur and this causes fixing of drain covers.