Explanation:
1) Initial mass of the Cesium-137=
= 180 mg
Mass of Cesium after time t = N
Formula used :
Half life of the cesium-137 =
= initial mass of isotope
N = mass of the parent isotope left after the time, (t)
= half life of the isotope
= rate constant

Now put all the given values in this formula, we get
Mass that remains after t years.

Therefore, the parent isotope remain after one half life will be, 100 grams.
2)
t = 70 years


N = 35.73 mg
35.73 mg of cesium-137 will remain after 70 years.
3)


N = 1 mg
t = ?

t = 224.80 years ≈ 225 years
After 225 years only 1 mg of cesium-137 will remain.
Answer:
Synthesis Reaction
Explanation:
It is a synthesis Reaction because it is taking little reactants and forming a big product!
Explanation:
The balanced chemical equation of the reaction is:

From the balanced chemical equation,
1 mole of propane forms ------ 3 mol. of
gas.
The molar mass of propane is 44.1 g/mol.
One mole of any gas at STP occupies --- 22.4 L.
Hence, 44 g of propane forms (3x22.4 L=) 67.2 L of CO2 gas at STP.
Answer:
Thus, 67.2 L of CO2 is formed at STP.
Reactant are those that combine or reacts to give products !!
so in combustion of ethane ; ethane and o2 are reactants so ... your answer is B !!
By nonmetals, metals, and gases