They are 50 stars in the U.S flag.
They are formed from erosion and weathering.
I think the first question is talking about the ionic compound Sodium sulfide and it’s formula is Na2S.
And for the second question, i’m pretty sure it’d be a positive charge
By equation of motion we have v = u + at
Where u = Initial velocity, v = final velocity, t = time taken and a = acceleration
Here v = 141 m/s, u = 17.7 m/s and t = 6 s
On substitution we will get
141 = 17.7+ 6a
So, a = (141-17.7)/6 = 20. 55 m/
Aceeleration = 20. 55 m/
along north direction.