Answer:- 9.4 minutes.
Solution:- Radioactive decay obeys first order reaction kinetics and the equation used to solve this type of problems is:
where, k is decay constant and t is the time. is the initial amount of the radioactive substance and N is the remaining amount.
Since the value of decay constant is not given, so we need to calculate it first from given half life by using the formula:
where stands for half life.
Given half life is 3.0 minutes.
So,
Let's plug in the values in the first order reaction equation and solve it for t.
It could also be written as:
k = 9.4 min
So, the radioactive substance would take 9.4 minutes to decay from 40.0 grams to 4.5 grams.
Answer:
negatively-charged particles.(ELECTRON) B
Explanation:
Electrons are the negatively charged particles of atom. Together, all of the electrons of an atom create a negative charge that balances the positive charge of the protons in the atomic nucleus
Br- + 2MnO4- + 2H+ → BrO3- + 2MnO2 + H2O
<h3>Further explanation</h3>
Given
MnO4- + Br- = MnO2 + BrO3-
Required
The half-reaction
Solution
In acidic conditions :
1. Add the coefficient
2. Equalization O atoms (add H₂O) on the O-deficient side.
3. Equalization H atoms (add H⁺ ) on the H -deficient side. .
4. Equalization of charge (add electrons (e) )
5. Equalizing the number of electrons and then adding the two half -reactions together
Oxidation : Br- → BrO3-
Reduction : MnO4- → MnO2
Br- + 3H2O → BrO3-
MnO4- → MnO2 + 2H2O
Br- + 3H2O → BrO3- + 6H+
MnO4- + 4H+ → MnO2 + 2H2O
Br- + 3H2O → BrO3- + 6H+ + 6e- x1
MnO4- + 4H+ + 3e- → MnO2 + 2H2O x2
- Equalizing the number of electrons and then adding the two half -reactions together
Br- + 3H2O → BrO3- + 6H+ + 6e-
2MnO4- + 8H+ + 6e- → 2MnO2 + 4H2O
Br- + 2MnO4- + 3H2O + 8H+ + 6e- → BrO3- + 2MnO2 + 6H+ + 4H2O + 6e-
Br- + 2MnO4- + 2H+ → BrO3- + 2MnO2 + H2O
<span>No of moles of Fe = Mass / Relative molar mass of Fe. So no of moles = 89.4/ 55.845 = 1.60. The. Chemical reaction is represented as follows. 4 Fe + 3 O2 which gives 2Fe2 O3 . This means that 4 atoms of Iron reacts with 3 atoms of Oxygen to produce Iron oxide. Hence 1.60*4 moles of Fe will need to react 1.6 * 3 moles of Oxygen to produce 2 moles of Iron oxide. Hence 4.8 moles of Oxygen will be required.</span>
Answer:
Well 50 of course
Explanation:
5 days per tasks is like saying 10 times 5 which is 50.