Answer:
The correct answer would be - c. A solid was added to water and the mixture was stirred until the solid was no longer visible
Explanation:
Photostabalizing is the process where a solid change its color in the presence of ultraviolet light, it is a chemical change, so the first option would not be the correct answer.
when two liquid or aqueous solutions are mixed together and form a solid substance, this reaction is known as precipitation and it is a chemical reaction too.
When a solid is placed in a liquid and after stirring it makes the solid vanish is a physical change known as dissolving character.
Thus, the correct answer is option C.
Answer:
Scientific experiments need to be repeated so that scientists can make sure the results are as accurate as possible.
Explanation:
The point of a scientific experiment is to find the answer to a question. If a scientist performs an experiment only one time, they might find an answer to their question. However, they might have messed something up, so the answer is completely wrong. Doing an experiment momre than once can help a scientist make sure that their answer is correct. I hope this helps!
"n" represents principal energy level or principal quantum number. Principal energy levels are then subdivided into sublevels. The level of principal energy level is always equal to number of sublevels. Therefore if <span>principal energy level</span> = 4, then there are also 4 sublevels present, namely: 4s, 4p, 4d and 4f sublevels.
Answer:
The answers to your questions are below
Explanation:
Physical change is when matter changes its form but is still the same substance.
Chemical change is when matter changes its composition.
iron and oxygen from rust It's a chemical change because iron and oxygen form a new compound different from the reactants.
iron is denser brightly when ignited
. This is a chemical property because iron reacts with oxygen.
oil and water do not mix
it's a physical change, oil and water are in touch but they do not react.
mercury melts at -39°C it's a physical property because mercury changes from solid to liquid but it still is mercury.
