A hot air balloon traveled 2.5 hours at a speed of 450 km/hr East. What distance did it travel?

Which object forms when a supergiant runs out of fuel? a red giant a black hole a white dwarf a neutron star

Why is retrograde motion an apparent motion

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!