Approximately how many asteroids that are 0.89 km in radius would it take to make a planet which has a radius of 6590.0 km?

A certain exoplanet has an eighth of the mass of the Earth and half its diameter. The escape velocity on the exoplanet is ________ times the escape velocity on the Earth.   A 1/4   B 1/2   C 2   D 4

The asteroid Pallas has a mass of 2.11 ✕ 1020 kg and an average radius of about 256 km (2.56 ✕ 102 km). What is its escape velocity (in m/s)? (Hints: Use the formula for escape velocity ; remember to convert units to m, kg, and s.)________ m/s

How many orders of magnitude do you need to grow in spatial scale (size) to form a planet? Let's take the extreme ends of this scale, from a dust particle of radius a = 10-6m to the gas giant Jupiter (you can round up its radius to the nearest ten to keep it simple). What else has this difference in order of magnitude? Maybe pick something that's not a length scale. Be creative!