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 :

Answer:
Y Q W Z X
Explanations:
The most reactive element is the element that will displace an element from it compound . The most reactive element will replace the less reactive element in it compound.
Q+ + Y Reaction occurs
Since the reaction occurs the element Y which is more reactive displaced element Q from it compound.
Q+W+ Reaction occurs
The reaction occurs, that means element Q replaces element w from it compound. Element Q is therefore more reactive than element W.
W+Z+ Reaction occurs
The reaction also occurs . This is an indication that element W replaces element Z in it compound. This means element W is very reactive than element Z.
X+Z+ No reaction
There is no reaction here. This is an indication that element X is less reactive than element Z. This is why element X can't displace element Y in it compound.
There are 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms in one molecule of C12H22O11.
In five molecules there are 60 carbon atoms, 110 hydrogen atoms, and 55 oxygen atoms.
Answer:
B. mass and height have the same effect on gravitational potential energy.
Explanation:
Both mass and height have the same effect on the gravitational potential energy of body.
Gravitational potential energy is the energy of a body due to that of another body. It usually the energy at rest in a body.
It is mathematically expressed as;
G.P.E = m x g x h
m is the mass
g is the acceleration due to gravity
h is the height
We see that both the height and mass are directly proportional to the gravitational potential energy and as such, they have the same effect.