When bismuth-212 undergoes alpha decay, it becomes which of the following?
asatine-208 + an alpha particle
lead-210 + an alpha particle
polonium-210 + and alpha particle
thallium-208 + and alpha particle

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When bismuth-212 undergoes alpha decay, it becomes ²⁰⁸Tl

Explanation: -

Mass number of ²¹²Bi = 212

Atomic number of ²¹²Bi = 83

When alpha decay occurs the mass number decreases by 4 and the atomic number decreases by 2.

Mass number of daughter = 212 - 4 = 208

Atomic number of daughter = 83 - 2 = 81

It is the atomic number of Thallium Tl.

Thus the daughter nucleide is ²⁰⁸Tl.

(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