State one important change or phenomenon that took place whe

State one important change or phenomenon that took place when the universe was about (a) 10^-6 seconds, (b) 10^-2 seconds, (c) 1 seconds, (d) 6 seconds

Solution

(a) When the universe is about 10^-6 seconds old, quarks combination started.

(b) When the universe is about 10^-2 seconds old , formation of and light Hadrons (protons and neutrons created) took place.

(c) When the universe is about 1 second old, Neutrinos decoupled as the binding enegy of neucleus exceeds the enrgy of photon. Electron, positron and neutrino created.

(d) When the universe is about 6 second old,Nucleosynthesis starts to begin. Protons and neutrons together form the nuclei of hydrogen, deuterium, helium and lithium.