The answer is A. Table salt is a pure substance.
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 :
The answer is definitely not 70.923
Electrons hold a negative charge, and anion refers to a negatively charged atom.
The answer is anion. Here's a way to help remember:
Cats have paws, and cations are "paws"itive (positive).