An exponential decay law has the general form: A = Ao * e ^ (-kt) =>
A/Ao = e^(-kt)
Half-life time => A/Ao = 1/2, and t = 4.5 min
=> 1/2 = e^(-k*4.5) => ln(2) = 4.5k => k = ln(2) / 4.5 ≈ 0.154
Now replace the value of k, Ao = 28g and t = 7 min to find how many grams of Thalium-207 will remain:
A = Ao e ^ (-kt) = 28 g * e ^( -0.154 * 7) = 9.5 g
Answer 9.5 g.
The type of reaction which occurs is referred to as redox reaction. This kind of reaction involve both oxidation and reduction.
Al(s) is oxidized to alluminium ions, while cu2+ is reduced copper metal.Reduction occurs at the cathode while oxidation occurs at the anode.
This problem is providing the length in inches of a rod and it is being required to convert it to centimeters. According to the following, the answer will be 43.7 cm:
<h3>Units conversion:</h3><h3 />
In science, we use units conversion to represent measurements in different types of units depending on a specific requirement. To do so, we use conversion factors based on equivalence statements, relating the required unit with the given one.
In this case, the equivalence statement between inches and centimeters is 2.54 cm = 1 in and we can use it to get the answer as shown below:

Learn more about units conversion: brainly.com/question/13016491
Okay so because of the difference in density a simple method for telling the difference between the two is to put a sample in a container with oil, because water has a higher density than the oil it would sink to the bottom but alcohol on the other hand is lighter than oil and would float on top of the oil.
However with this question I think that what you would do is use the ice to find out what the substance is, it would float on top of the liquid if it were water because the water is denser than ice but the ice would sink if it was alcohol because the alcohol is less dense than ice.
I hope this helps you, good luck : )