Answer:
Point number 3.
Explanation:
Volcanism can be studied to found out evidence of the internal structure of the Earth.
The refractive index for glycerine is

, while for air it is

.
When the light travels from a medium with greater refractive index to a medium with lower refractive index, there is a critical angle over which there is no refraction, but all the light is reflected. This critical angle is given by:

where n1 and n2 are the refractive indices of the two mediums. If we susbtitute the refractive index of glycerine and air in the formula, we find the critical angle for this case:
its period should be the amount it takes to cycle from cycle to cycle so it would be 10 and your frequency would have to be calculated by taking 10 and dividing by 2 since that is how many cycles you have done so your frequency is 5
plz mark me brainliest
heat from water goes into air in ball
air expands
ping goes the dent
I see a pillow
But you see...this bobcat
Cute ain’t it?