a) →
b) →
<h3>What are half-reactions?</h3>
The half-reaction method is a way to balance redox reactions. It involves breaking the overall equation down into an oxidation part and a reduction part.
a)
→
=
= -0.83 - (-2.71) =1.88V
b)
→
=
=-0. - (0.8) =-0.8V
Learn more about the half-reactions here:
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The amount left after 20 years = 154.15 mg
<h3>Further explanation </h3>The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually radioactive elements have an unstable atomic nucleus.
The main particles are emitted by radioactive elements so that they generally decay are alpha (α), beta (β) and gamma (γ) particles
The decay formula for isotope :
Then for t=20 years, the amount left :