This question is testing to see how well you understand the "half-life" of radioactive elements, and how well you can manipulate and dance around them. This is not an easy question.
The idea is that the "half-life" is a certain amount of time. It's the time it takes for 'half' of the atoms in any sample of that particular unstable element to 'decay' ... their nuclei die, fall apart, and turn into nuclei of other elements.
Look over the table. There are 4,500 atoms of this radioactive substance when the time is 12,000 seconds, and there are 2,250 atoms of it left when the time is ' y ' seconds. Gosh ... 2,250 is exactly half of 4,500 ! So the length of time from 12,000 seconds until ' y ' is the half life of this substance ! But how can we find the length of the half-life ? ? ?
Maybe we can figure it out from other information in the table !
Here's what I found:
Do you see the time when there were 3,600 atoms of it ? That's 20,000 seconds.
... After one half-life, there were 1,800 atoms left. ... After another half-life, there were 900 atoms left. ... After another half-life, there were 450 atoms left.
==> 450 is in the table ! That's at 95,000 seconds.
So the length of time from 20,000 seconds until 95,000 seconds is three half-lifes.
The length of time is (95,000 - 20,000) = 75,000 sec
3 half lifes = 75,000 sec
Divide each side by 3 : 1 half life = 25,000 seconds
There it is ! THAT's the number we need. We can answer the question now.
==> 2,250 atoms is half of 4,500 atoms.
==> ' y ' is one half-life later than 12,000 seconds
==> ' y ' = 12,000 + 25,000
y = 37,000 seconds .
Check: Look how nicely 37,000sec fits in between 20,000 and 60,000 in the table.
As I said earlier, this is not the simplest half-life problem I've seen. You really have to know what you're doing on this one. You can't bluff through it.
A chemical reaction refers to an interaction between two or more chemical species that leads to the formation of other new chemical species.
There are many types of chemical reactions. The type shown above is called a double replacement reaction. In this type of reaction, ions exchange partners in the product.
A chemical reaction is said to be balanced when the number of atoms of each element on the left hand and right hand sides of the reaction equation are exactly the same.
you can do anything if you put your mind to it. Also, school is not everything in life there are amazinng things in life that you need school for. you got this.
Heat transfer to a beaker on a hot plate is an example of conduction.
Explanation:
Conduction is a process where heat is transferred from one particle to another particle. Conduction is mainly possible in case of solids.In case of solids the atoms as well as the molecules are tightly packed through which the kinetic energy can easily pass. Conduction takes place when both the objects are touching each other. But in case of liquids molecules are loosely packed as a result convection takes place.
