So what do you want me to do
Explanation
Answer:
a pure substance consists only of one element or one compound
a mixture consists of two or more different substances, not chemically joined together.
examples:
pure substance : Hydrogen gas - Diamond - Gold metal.
mixture : water and oil - mixtures of sand and water - trail mix
Explanation:
...............................................c
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
Answer: Hmmmmm that's crazy....
There are a couple of equations one could use for this type of problem, but I find the following to be the easiest to use and to understand.
Fraction remaining (FR) = 0.5n
n = number of half lives that have elapsed
In this problem, we need to find n and are given the FR, which is 1.56% or 0.0156 (as a fraction).
0.0156 = 0.5n
log 0.0156 = n log 0.5
-1.81 = -0.301 n
n = 6.0 half lives have elapsed
Explanation:
Just wanted to help. Hopefully it's correct wouldn't want to waster your time ;)
