Question

A scientist carried out several different procedures, each of which caused a change in matter. Select each procedure that is likely a chemical change.
{1}Salt crystals were crushed into a fine powder.
{2}Bubbles were produced when iron was placed in acid.
{3}Two liquids were combined, and a solid appeared.
{4}A piece of metal melted when it was heated.
{5}A white substance turned blue when water was added.

Answer 1

Answer: Option (2), (3) and (5).

Explanation:

Chemical change: It is a chemical reaction in which arrangement of atoms of one or more than one substance changes to give new substances as a product.Chemical change can be in form of : color change, formation of precipitate, formation of bubbles.

In option (2), bubbles were produced when iron was placed in acid which means gas was released on adding iron to acid.Yes, it is a chemical change.

In option (3), solid that is precipitate is obtained as a product from the reaction between two liquids which means that change in arrangement of atom had taken place.Hence, a chemical change.

In option (5), white substance turned blue when water was added. Color of white solid changes to blue which means that chemical change has taken place.

So, option are (2), (3) and (5) are examples of chemical changes.