Answer:
6.502 x 10²⁴ atoms.
Explanation:
First we <u>convert 158.4 g of CO₂ into moles</u>, using <em>carbon dioxide's molar mass</em>:
- 158.4 g ÷ 44 g/mol = 3.6 mol CO₂
Then we<u> calculate how many CO₂ molecules are there in 3.6 moles</u>, using <em>Avogadro's number</em>:
- 3.6 mol CO₂ * 6.023x10²³ molecules/mol = 2.168x10²⁴ CO₂ molecules
As there are 3 atoms per CO₂ molecule, we<u> triple the number of CO₂ molecules in order to get the answer</u>:
- 2.168x10²⁴ CO₂ molecules * 3 = 6.504x10²⁴ atoms
The closest answer is the third option, 6.502 x 10²⁴ atoms.
The molar mass of CuCl2 is 134.45 g/mol; therefore, you divide 2.5 g of CuCl2 by 134.45 g of CuCl2 leaving you with 0.019 moles
Answer:
1.25 g
Explanation:
Now we have to use the formula;
N/No = (1/2)^t/t1/2
N= mass of cesium-137 left after a time t (the unknown)
No= mass of cesium-137 present at the beginning = 5.0 g
t= time taken for 5.0 g of cesium-137 to decay =60 years
t1/2= half life of cesium-137= 30 years
Substituting values;
N/5= (1/2)^60/30
N/5= (1/2)^2
N/5= 1/4
4N= 5
N= 5/4
N= 1.25 g
Therefore, 1.25 g of cesium-137 will remain after 60 years.
Explanation:
When two substances chemically combine together then it results in the formation of a new compound whose chemical properties are different from the reactant species.
Thus, there will be change in the chemical composition when reactants combine together.
Therefore, we can conclude that if two substances combine to form a new substance with different properties, a chemical change has occurred.