The periodic table is an arrangment of the chemical elements, ordered by atomic number, into families, and by doing so illustrates the periodic properties of the elements. If we review the elements found in the second column of the periodic table, the alkali
earth metals, we know one characteristic common to all elements in this family, besides being metals, is that they are
ng
5
A)
solid at room temperature.
B)
not very reactive elements.
found deep in the layers of the mantle.
D)
react readily with other metals to form compounds.

insects!

explanation:

answer: a. same unit

explanation:

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.

the answer is 12 as i may remember

: )