Answer: b} The exact time when an individual atom will decay can be accurately predicted.
c} After each half-life, the amount of radioactive material is reduced by half.
Explanation:
All radioactive decay  follows first order kinetics.
Rate law expression for first order kinetics is given by:
 
where,
k = rate constant
t = time taken for decay process
a = initial amount of the reactant
a - x = amount left after decay process
Expression for calculating half life, which is the time taken by the half of the reactants to decompose is:

 
        
                    
             
        
        
        
Answer:
See explanation
Explanation:
Electron affinity is the energy released when an extra electron is added to a neutral gaseous atom. A negative value of electron affinity indicates that energy is given out and vice versa.
Metals have positive electron affinity since electrons rarely accept electrons, so;
Na(g)+ 1e^- → Na^-(g)      positive
Mg(g)+1e^- → Mg^-(g)      positive
For the last case; Br(g)+ 1e^- → Br^-(g), the electron affinity for the non-metals is negative. hence the answer
 
        
             
        
        
        
<span>during photosynthesis the co2 is converted into sugar
</span><span> 6 carbon compound that immediately splits into 2 molecules of 3-phosphoglycerate. 
</span><span>3 CO2 + 9 ATP + 6 NADPH + 6 H+ → C3H6O3-phosphate + 9 ADP + 8Pi + 6 NADP+ + 3 H2O
</span>hope it helps