The electron configuration notation for Na is:
1s 22s 22p 6
1s 22s 22p 5
1s 22s 22p 63s 2
1s 22s 2
1s 22s 22p 63s 1

The answer to your question is the last one.

Explanation:

The Electron configuration of Na

Sodium is an Alkali Metal with 11 electrons. This metal is located in group lA, which means that must have only one electron in its outermost shell

1s²2s²2p⁶      This electron configuration has 8 electrons in its outermost shell.

1s²2s²2p⁵         This electron configuration has 7 electrons in its outermost shell

1s²2s²2p⁶3s²    This electron configuration has 2 electrons in its outermost shell.

1s²2s²                  This electron configuration has 2 electrons in its outermost shell.

1s²2s²2p⁶3s¹     This electron configuration has 1 electron in its outermost shell and 11 electron in total, so this is the right answer.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied