Mars.
Venus is closest to earths planet size.
Chance. It depends on the rotational energy transferred to the planet back when it was being created ... less the amount that has been transferred to the moon since it was formed.
Mercury is earths brother planet because Venus is earths sister planet.
Which planet?
no
venus does because it rotates as earth does and it is earths twin baby
It is Venus.
Rigel is a star, not a planet, so it does not have a day.
9.8
Core
I believe there are because were not the only planet