If there is 8g substance before a physical change, how much will be afterwards?
0g
4g
8g
16g

8g

Explanation:

The law of conservation of mass explains that the mass of substances before a physical change is the same as the mass after the change i.e mass is always conserved in nature.

Hence, the physical change will convert 8 grams of the reacting substance to 8 grams of products as well.

For instance:

Consider a change: A --> C

Once the mass of "A" is 8g, "C" the product of the physical change will also have a mass of 8g.

For the answer to the question, what is the frequency of the wave if  wave crests are 8.0 meters apart. the time for a complete wave to pass by is 4.0 seconds. the markings on the post submerged in water indicate that the water level fluctuates from a trough at 6.0 meters to a crest at 9.0 meters.?
the answer is 3.0m