Question

by the help of which observation, can it be known that any chemical reaction has taken place?
$\\ please \: answer \: it \: fast \\ it \: is \: urgent$
​it is of class 10

Answer 1

Following are the observations to determine whether the chemical reaction has taken place or not:

Change in colou

Evolution of gas

Changee in temperature

Formation of precipitate

Change in pH

Answer 2

Answer:

sodium chloride with hydrogen +h2o