Answer:
Its answer is
The atomic symbol of an element surrounded by valence electrons.
Explanation:
a) since force = mass * acceleration
f= 900 * 0 (because constant speed = 0 acceleration)
similarly b) f = 0
1 particles have got forces of attraction between them
2 they vibrate and rotate at a fixed point
3 they gan heat energy in order for them to melt
4 particles are closely packed together