Question

how does matter change? that was a question students were investigating in class. each group had an experiment to carry out and then determine if the changes observed indicated a physical or chemical change. here is one groups experimental procedure and results. what type of change occurred? cite any appropriate evidence. a chemical; the alka - seltzer tablet dissolved and disappeared. b chemical; nothing new was formed. c chemical; a gas was produced and the temperature changed. d physical; the alka - seltzer tablet dissolved and disappeared.

Explanation:

A chemical change is characterized by the formation of new substances, production of gas, or a change in temperature. When an Alka - Seltzer tablet is added to water, a chemical reaction occurs producing carbon - dioxide gas and changing the temperature. Just dissolving and disappearing could be a physical change in some cases, but the gas production and temperature change indicate a chemical change. Option B is incorrect as a new substance (gas) is formed in a chemical change.

Answer:

C. Chemical; a gas was produced and the temperature changed.