Answer:
A = 349 g.
Explanation:
Hello there!
In this case, since the radioactive decay kinetic model is based on the first-order kinetics whose integrated rate law is:
We can firstly calculate the rate constant given the half-life as shown below:
Therefore, we can next plug in the rate constant, elapsed time and initial mass of the radioactive to obtain:
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Answer:
D: a heterogeneous mixture with components of varying sizes
Heterogeneous mixture is a combination of substances that doesn't have uniform composition and properties. Just by looking at the mixture you can differentiate the compounds because they are so different. Using a sieve, allows the components with different sizes to separate, while one is retained, the others can pass the holes in the sieve.
Explanation:
You have to be very careful with this question. A change in mass can also occur in chemical changes especially if you have too much of something. For example
CH4 + 1.5 02 ===> CO2 + H2O
If you have too much of either CH4 or O2, there will be some CH4 or O2 left over. There has been a change in mass that you have too much of.
However that is not the point of the question. It is just something you need to be aware of.
Suppose you have a piece of aluminum and you take a course grinder after it. You will change the texture of the side you took the grinder to. If the aluminum has been anodized (a color has been put on it's surface), you may grind the color off or if it is just plain aluminum, you may roughen the surface, but you won't change what the aluminum will do chemically.
You may need only a small portion of the aluminum and you grind off just what you need. That will change the mass of both what you took off and the piece that you want, but the aluminum will still do whatever chemical property you need to use.
So you can change both texture and mass without changing the chemical properties of the substance whose mass or texture you are changing.
