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 : )
Sodium would form Na+
Oxygen would form O-2
Phosphorus would form -3 or +5
Sodium and oxygen would combine to form ionic bonds because one is a metal and the other is non-metal, while Phosporus and oxygen would combine to form covalent bonds because they are both non-metals.
The answer is 3.
<span>The relation between number of half-lives (n) and decimal amount remaining (x) can be expressed as:
</span>

We need to calculate n, but we need x to do that. To calculate what p<span>ercentage of a radioactive species would be found as daughter material, we must calculate what amount remained:
1.28 -</span> 1.12 = 0.16
If 1.28 is 100%, how much percent is 0.16:
1.28 : 100% = 0.16 : x
x = 12.5%
Presented as decimal amount:
x = 0.125
Now, let's implement this in the equation:
<span>

</span>
Because of the exponent, we will log both sides of the equation:


<span>

</span>


Therefore, 3 half-lives have passed <span> since the sample originally formed.</span>