Changes in matter occur every day. There are two types of ways matter can be altered; physically and chemically. Physical changes do not change the composition of the matter while chemical changes occur when one or more substances turn into a completely new substance. Physical changes can be seen through an altering of the substances physical property. A substances physical property is observed and measured without changing the composition of the subject. Descriptive words that would help to identify a substance’s physical property include hard, soft, brittle, flexible, heavy, and light just to name a few. Let’s say you’re eating, throughout the day your stomach starts to growl that is what happens when your stomach is digesting your food. Digestion is an example of chemical change. Chemical change happens every day and more than half the time we don’t realize it whether it’s metal starting to rust, or our food starting to rot. Physical change can happen when your popsicle starts to melt, or your water starting starting to boil. These are examples of physical change.
Answer: The new pressure is 3 psi.
Explanation:
Given: 
= 12 psi, 
= ?, 
Formula used is as follows.
Thus, we can conclude that the new pressure is 3 psi.
Answer:
H(aq) + NO3 (aq) + HF(aq)
Explanation:
In the given mixture of HNO3 (Nitric Acid) and HF (hydrofluoric acid) in water the major species present are H(aq) + NO3 (aq) + HF(aq).
On the reaction of HNO3 (Nitric Acid) and HF (hydrofluoric acid) in water , it will give a polar solution and will form a homogenous mixture.
Hence, the correct answer is "H(aq) + NO3 (aq) + HF(aq)".
Answer:
a pure substance consists only of one element or one compound
a mixture consists of two or more different substances, not chemically joined together.
examples:
pure substance : Hydrogen gas - Diamond - Gold metal.
mixture : water and oil - mixtures of sand and water - trail mix
Explanation:
