A student added a piece of limestone to a solution of hydrochloric acid. Based on observations, the student infers that a chemical reaction took place. Which of the following is an observation that directly supports the inference? O A. Bubbles formed.
OB. The limestone dissolved.
O C. The solution became doudy.
OD. The volume of the solution increased

A. Bubbles formed

Explanation:

When a student added a piece of limestone to a solution of hydrochloric acid, bubbles are formed.

The bubbles are as a result of the CO2 gas that is formed.

Below is the reaction:

CaCO3+2HCl → CO2+H2O + Ca++ + 2Cl-

From the left hand side, we can see that the reaction is with limestone and hydrochloric acid. Their reaction forms carbon dioxide gas (CO2), water (H2O), dissolved calcium (Ca++) and dissolved chlorine (Cl-) on the right hand side.

With due observation, bubbles will be seen evolving from the reaction. These bubbles formed is the carbon dioxide gas which reveals that a reaction is taking place.

what is a theme?

ans: the implicit idea of a written work of literature is called a theme.

so, the only theme of "birdfoot's grampa" by joseph bruchuc is that as a human being one should always remember the value of every life on earth.

the grampa is stopping the car again and again to save those little toads from washing away in the heavy rain is an act of kindness and humanity.

i think its d

hope that is