Answer:
Half life of phosphorous-32 = 14 days
Explanation:
Given data:
Total mass of phosphorous-32 = 2.0 g
After 42 days mass left = 0.25 g
Half life of phosphorous-32 = ?
Solution:
First of all we will calculate the number of half lives passed.
At time zero = 2.0 g
At first half life = 2.0 g/2 = 1.0 g
At 2nd half life = 1.0 g/2 = 0.5 g
At 3rd half life = 0.5 g/2 = 0.25 g
Half life:
Half life = T elapsed / half lives
Half life = 42 days/ 3
Half life = 14 days
D. There is one atom of sulfur and three atoms of oxygen.
The "tri" in trioxide indicates three so there are three atoms of oxygen. As nothing is said about the sulfur, there is just one atom.
Hope this helps!!
Answer:
A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does. ... In a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.
Explanation:
This problem applies Hess' Law to come up with the final reaction from a series of reactions given. Equation (1) stays as it is. Equation (2) should be inverted and divided by 2. Equation (3) is simply divided by 2. The energies should also correspond to the operations. Adding the net energies of each reaction, the total energy is 155.65 kJ. Hence, the answer is A.
