Answer : The substances half life in days is, 5.6 days.
Step-by-step explanation :
Half life : It is defined as the amount of time taken by a radioactive material to decay to half of its original value.
All radioactive decays follow first order kinetics.
The relation between the half-life and rate constant is:

where,
k = rate constant = 0.1235 per days
= half-life
Now put all the given values in the above formula, we get:


Thus, the substances half life in days is, 5.6 days.
Selection B is appropriate.
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The signs of the coefficients tell you the binomial factors must have both signs positive (selections B and C only). Selection B produces an x-term that is 15x+15x=30x (as we want); selection C produces an x-term that is 45x+5x=50x (not what we want).
Answer:
Step-by-step explanation:
8/3=3(c+5/3)
multiply both sides by 3
8=9(c+5/3)
divide both sides by 9
8/9=c+5/3
subtract 5/3 from both sides
c=8/9-5/3
change 5/3 to 15/9
c=8/9-15/9
c=-7/9
1/3y + 28 = -5
Subtract 28 from both sides:
1/3y = -33
Multiply both sides by 3:
y = -99
The answer is E) NOTA