1 does this equation represent a physical or chemical change 2 give one reason that supports if it is a physical or chemical change

3 does this chemical reaction follow the law of conservation of matter

4give one reason that supports if this chemical reaction follows the law of conservation

WILL GIVE 20 POINTS AND BRAINLIES PLZ HELP

this one:

as we gain mass the force of gravity on us increases.

pls mark me as the ! : d

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.