Answer:
5m/s²
Explanation:
Given parameters:
Initial velocity = 10m/s due east
Final velocity = 30m/s due east
Time = 4s
Unknown:
Acceleration of the car = ?
Solution:
Acceleration is the rate of change of velocity with time.
Mathematically;
Acceleration = 
v is the final velocity
u is the initial velocity
t is the time taken
Insert the parameters and solve;
Acceleration = 
= 5m/s²
Molecular mass of nitrogen, N2 = 2*14 = 28
molecular mass of hydrogen, H2=2*1 = 2
Molecules of both elements contain 2 atoms, so the ratio of molecules is the same as the ratio of atoms.
From the molecular masses above,
ratio of number of molecules = ratio of molecular masses, therefore
7g N2 : x g H2 = 28:2
cross multiply:
x=7*2/28=0.5 g of Hydrogen has the same number of atoms as 7 g of nitrogen (at room temperatures)
Carbon atomic number ⇒ 6
Carbon mass number ⇒ 12.
Carbon atomic number - Carbon mass number = number of neutrons.
12 - 6 = 6 neutrons.
Proton charge ⇒ +1
The total charge of the nucleus of a carbon atom ⇒⇒⇒ +6.
So the naswer is (3) +6
