Atoms of the same element that have different masses are called

ISOTOPES

Explanation:

As we know that the atoms of same element with different number of protons is known as ISOTOPES

So here we can say that

here in above example the two atoms are same with same atomic number z

but the mass number is different in it

As we know that

mass number = number of proton + number of neutrons

So isotopes must have different number of neutrons present in the nuclei

explanation:

considering the bohr theory, the type of connection that requires the transfer the answer conuldn't be right

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.