Question

Which of the following is an example of a physical change?Select one:a.Mixing baking soda and vinegar together, which causes bubbles and foam.b. A glass cup falls from the counter and shatters on the ground.c.Lighting a piece of paper on fire and the paper burns up and leaves ashes.d.Fireworks exploding.

Answer 1

Let's analyze eqach situation.

(a) the mixutre of baking soda and vinegar creates gas, which can be seen by the bubles and foam. This is a change of property occuring, which menas it is a chemical change.

(b) A glass cub shatters but what happened in thsi case is just that we broke down the glass into smaller pieces, but their properties are still the same, they are transluscent solid. So, this is a physical change.

(c) Burning something is the result of a reaction of it with oxigen and the release of energy. As we can see, the paper changed its properties from the start situation, an evidence of chemical change.

(d) Fireworks are similar to a controlled explosion, it is a reaction that form gases and expand and anso release enegy in the form of light, which is evidence of chemical change.

So, the only one that is physical change is item B.