Which substance is reduced ?
Cl^2 +2KBr= 2KCl + Br2

Initially Br is in -1 oxidation state and Cl in 0 oxidation state. Finally Cl is in -1 o.s. and Br in 0.

This means that Br has oxidised from -1 to 0 and Cl is reduced from 0 to -1.

KBr is reducting agent as it helps Cl to reduce.

Cl2 is oxidising agent as it helps Br to oxidise.

Explanation:

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.

(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