Radioactive elements inside the planet release heat now, but why was so much more heat released earlier in

Earth's history that is released now?

Which metal exist in liquid state and can be cut with knife ?

An atom's configuration based on its number of electrons ends at 3p4. another atom has seven more electrons. starting at 3p, what is the remaining configuration? 3p63d34s2 3p43d54s2 3p64s23d3 3p44s23d

Why is retrograde motion an apparent motion