Explanation:
compound is already together use your brain man you take multiple things. to make lemonade aka a mixture of powder and water cmon man u gotta think about it logically
think about like this a bartebder asjs you what drink your having what is he going to do next ? hes going to make the drink so you can have another right? yha
observe what happens next
the bartender grabs a cup and goes to the ice and scoops it up he takes a bottle of vodka and puts it into the shot cup "a preset cup for alcohol measurement " he takes stawberry puraee (strawberry mix) and pyrs it into the drink and mixes it around by shaking it . puts a extractor on top of it and takes a glass and pours the drink in front of you into the glass. you dont see the vodka in there do you ? no you dont because its mixed in there same thing with lemonade.
Answer:- 9.4 minutes.
Solution:- Radioactive decay obeys first order reaction kinetics and the equation used to solve this type of problems is:
where, k is decay constant and t is the time. 
is the initial amount of the radioactive substance and N is the remaining amount.
Since the value of decay constant is not given, so we need to calculate it first from given half life by using the formula:
where 
stands for half life.
Given half life is 3.0 minutes.
So, 
Let's plug in the values in the first order reaction equation and solve it for t.
It could also be written as:
k = 9.4 min
So, the radioactive substance would take 9.4 minutes to decay from 40.0 grams to 4.5 grams.
4 moles of sodium because you originally have 2.0 moles of Na2SO4 and you set that up at the beginning of the (what we called) train tracks. Then diagonally from that, on the bottom you put 1 mol of Na2SO4 to cancel the units. Then above that you have 2 moles of sodium because that is how many there are in the equation that they gave (the Na2 part). Then its just like a fraction, you multiply the top by the top and the bottom by the bottom, which would give you 4moles/1 or just 4 moles Na. I hope that helps
