Astronauts and objects inside an orbiting spacecraft appear weightless mainly because:

1. At the height of a space station, $g$ is only about 11% less than its surface value, not zero. 2. So height is not the reason for weightlessness. 3. The only force on the orbiting craft is gravity, so the craft, the travellers and the objects are all in free fall. 4. Since free-fall velocity is independent of an object's properties, a released object stays put relative to the astronaut and seems weightless. 5. Absence of air and zero $g$ are misconceptions, so those options are wrong. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 1 "Gravitation", p.23_