The sample will lose half of its mass after 4 hours. The half life.
82=4
The sample will lose half of the remaining four after another half life.
42=2 Hope this helps! :)
CH3COONa+HBr ----> NaBr + CH3COOH
CH3COO⁻ +H⁺ ------> CH3COOH , because CH3COOH is a weak acid
