Answer:
Option C. Triple the number of moles
Explanation:
From the ideal gas equation:
PV = nRT
Where:
P is the pressure
V is the volume
n is the number of mole
R is the gas constant
T is the absolute temperature.
Making V the subject of the above equation, we have:
PV = nRT
Divide both side by P
V = nRT / P
Thus, we can say that the volume (V) is directly proportional to both the number of mole (n) and absolute temperature (T) and inversely proportional to the pressure (P). This implies that and increase in either the number of mole, the absolute temperature and a decrease in the presence will cause the volume to increase.
Thus, the correct option is option C triple the number of moles. This can further be seen as illustrated below:
Initial volume (V1) = 12 L
Initial mole (n1) = 0.5 mole
Final mole (n2) = triple the initial mole = 3 × 0.5 = 1.5 mole
Final volume (V2) =?
From:
V = nRT / P, keeping T and P constant, we have:
V1/n1 = V2/n2
12/0.5 = V2/1.5
24 = V2/1.5
Cross multiply
V2 = 24 × 1.5
V2 = 36 L.
Thus Option C gives the correct answer to the question.
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.
Answer:
D. It is converted into kinetic energy.
Explanation:
When a book is dropped from a desk to the floor, the potential energy of the book is converted to kinetic energy as it falls.
- Potential energy of a body is the energy due to the position of the body.
- At a particular height, the potential energy is maximum.
- A body with mass and moving with velocity will have kinetic energy
- As the book drops through the height, to conserve energy, the potential energy is converted to kinetic energy.
b. increase in surface area
<h3>Further explanation</h3>
Given
Speeding up a chemical reaction
Required
Factors used to speed up reactions
Solution
There are several factors that influence reaction kinetics :
1. Concentration
2. Surface area
3. Temperature
4. Catalyst
5. Pressure
6. Stirring
Temperature is related to the kinetic energy of the particles. Heat is absorbed causes the particles of matter to move faster so that the reaction can take place faster
The enlarged surface area of the reactants causes more particles to react with other particles.
50 g square block of sulfur can be broken into small pieces or powdered so that more particles come into contact with each other
pH: 11.8750612634
pOH: 2.12493873661
[H+]: 1.33333333333E-12
[OH-]: 0.0075
BASE
