Sulphurous acid is not a reaction (chemical or physical); the sulphurous acid (H2SO3) is a chemical compound.
The chemical formula for sulphurous acid is H2SO3.
Sulphuric acid = H2SO4
chemical reaction
Sulphur dioxide (SO2) reacts with oxygen in the air to form sulphurous acid (H2SO3). This reaction occurs when SO2 dissolves in water, creating a weak acid known as sulphurous acid. Sulphurous acid is commonly found in the atmosphere as a result of industrial processes and volcanic emissions.
The reaction is:Mg + H2SO4 = MgSO4 + H2
A physical reaction is when no new substances are formed, there is a change of state eg ice melting to a liquid. A chemical change is when the reaction forms a new substance. eg gas bubbles. An acid reaction can be both. You need to look at the reaction taking place, look for change of state (physical) or any colour change or gas bubbles (chemical).
A neutralization reaction is a chemical change.
Sulphur dioxide reacts with water to form sulphurous acid. The word equation for this reaction is: sulphur dioxide + water --> sulphurous acid.
Testing stones with acid is a chemical change because it involves a chemical reaction between the acid and the minerals in the stone, resulting in a new substance being formed.
Chemical property: Reacts with acid to form a salt and water through a neutralization reaction. Physical property: Acid-base indicators change color in the presence of an acid.
Adding water (which is not a reactant) is a physical process.
Adding a base to an acid or vice versa in changing the chemical properties of that solution. In both cases you are neuralizing the solution. There might be a physical change as well, but it would depend on what chemicals where mixing. But this reaction will definitely have a chemical change.