A sample of compound A was heated in a Bunsen flame and no flame colour. On addition of sodium hydroxide solution to a solution of A, a white precipitate formed that did not re-dissolve when more sodium
hydroxide was added. When nitric acid was added to a solution of A, the mixture bubbled giving a gas that
turned limewater cloudy.
a Give the formula of the positive ion in A.
b Give the formula of the negative ion in A.
C Give the formula compound A.
Hi

Both the observations are a type of chemical change.

Explanation:

A physical change is defined as the change which occurs when there is no change in the composition of a substance. The physical state of the substance is changed. No new substance is formed.

A chemical change is defined as the change which occurs when there is change in the composition of a substance. New substance is formed at the end of the reaction.

There are many indicators which show us that a chemical change is happening in the reaction:

For the reaction of vinegar and baking soda, the equation follows:

For the observations given in the question:

Observation 1. In this observation, the temperature is being decreased because this reaction is an endothermic process. As there is change in temperature, hence it is considered as a chemical change.

Observation 2: In this observation, gas bubbles are formed due to the release of carbon dioxide gas. As there is formation of bubbles in this reaction. Hence, it is considered as a chemical change.