Answer:
Let No be initial no of atoms
N = N0 / 2 after 1 half-life
N = N0 / 4 after 2 half-lives
So after 2 half-lives 20 of the 80 atoms remain
Answer:
Boyle's Law

Explanation:
Given that:
<u><em>initially:</em></u>
pressure of gas, 
volume of gas, 
<em><u>finally:</u></em>
pressure of gas, 
volume of gas, 
<u>To solve for final volume</u>
<em>According to Avogadro’s law the volume of an ideal gas is directly proportional to the no. of moles of the gas under a constant temperature and pressure.</em>
<em>According to the Charles' law, at constant pressure the volume of a given mass of an ideal gas is directly proportional to its temperature.</em>
But here we have a change in the pressure of the Gas so we cannot apply Avogadro’s law and Charles' law.
Here nothing is said about the temperature, so we consider the Boyle's Law which states that <em>at constant temperature the volume of a given mass of an ideal gas is inversely proportional to its pressure.</em>
Mathematically:



Answer: A.The ocean is colder than the land
Explanation:
Based on the information provided in the question, we are informed that Agustin visits Panama City, Florida, during the month of May and that he feels a shore breeze blowing from the ocean onto the beach.
The reason for the shore breeze is simply due to the fact that the ocean is colder than the land. Since the ocean is colder, anyone who goes to the beach will feel the breeze.
When you use a wrench to tighten or loosen a nut on a bolt, you are
applying torque. It is measured in units of force times distance.
A force of F newtons pulling on a handle of L meters in length would
supply a torque of F L newton-meters.
More technically, torque is the vector cross product of force times
perpendicular distance from the object, F x r = F r sin @