Answer:
Other comparisons of the legislative process in both chambers shows that:
In both House and Senate: Committees review and mark up bills.
In the House of Representatives: Bills are introduced by the reading clerk.
In Senate: Bills can be filibustered.
In Senate: Only related amendments can be attached to bills.
In both House and Senate: Unrelated riders can be attached to bills.
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Sr will always have 38 protons because that is its atomic number. Normally Sr has 38 protons and 49 neutrons yielding an atomic mass of 87. unless you are dealing with an isotope of Strontium in which 3 additional neutrons would give you the 53 neutrons in your answer, (38p, 52n).
Because 25% is half of 0.5 and the half life of
is given as 5,715, the time it takes to reach this amount should just be double the half life: 11430 years.
However, in other cases the problem may not have easy numbers, so below is a more mathematical approach.
The half life formula is
.
Solving for t gives:

Given information:

Plug in given values and solve for t.

With correct significant figures, this would be 11000 years.
well an example, if the half-life of a 50.0 gram sample is 3 years, then in 3 years only 25 grams would remain. During the next 3 years, 12.5 grams would remain and so on.
B) Exothermic
The reaction released heat energy to its surrounding, thus, it was exothermic.
"exo" is to expel or put outside
"thermic" means heat