I believe the first space is 1. alloys, and the second space is also 1. main. I don't know for sure but I hope this helps.
Kepler's Laws of Planetary Motion. While Copernicus rightly observed that the planets revolve around the Sun, it was Kepler who correctly defined their orbits.
Sorry about the holds, copied it from google...
Because they have a full outer shell and they are both noble gases...Because the outer shell has attained stable electronics configuration of octate rule this it is with noble gas as helium.
Hope I helped!
Concave is not a type of mechanical wave because it doesn’t need a medium for propagation.