I believe that sugar will desolve the fastest because of the room temperature
The results of Dominic and Eva's experiment is unreliable and can lead to a pseudoscientific claim primarily because they did not repeat their tests multiple times. Although, they used the same type of stopwatch in recording the time it takes for the chemical reaction to occur, they have different reactions times. Thus, it would have been better if they conducted several trials then obtained the average of their results.
Elements of iodine are fluorine, chlorine, bromine, and astatine.
Unfortunately, we have not fully solved the 'nitrogen problem'. To do this, we must halve the amount of nitrogen we dump into the environment by mid-century or our ecosystems will face epidemics of toxic tides, lifeless rivers, and dead oceans. And that to do that will require, among other things, almost doubling the efficiency of nitrogen use on the world’s farms.
If you mean the number of Significant Figures/Digits in 23.45, it would be 4. This is because every single non-zero digit is counted as a significant figure