Their Period number is common means their "Principal Quantum Numbers" are same
Hope this helps!
First satellite was Sputnik and it was a race then to send satellites!! Everyone starts experimenting how to launch.
first try was on a dog , Laika !! It was send to space as it is long after sputnik is placed in orbit !!
Now you know everyone knows rocket science and the most active are ISRO (India) and NASA (USA) !!
Answer:
The mantle
Explanation:
The mantle is a plastic solid of varying densities which allow convection currents to flow molten rock towards the earth's surface resulting in volcanic activity, tectonic plate movement, earthquakes, and movement of continents.
They differ from each other<span> in wavelength. Wavelength is the distance between </span>one wave<span> crest to the next. </span>Waves<span> in the </span>electromagnetic<span> spectrum vary in size from very long radio </span>waves<span> the size of buildings, to very short gamma-rays smaller </span>than<span> the size of the nucleus of an atom.</span>
