Answer:
B
Explanation:
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In order for a certain reaction to be spontaneous, the change in Gibb's free energy must be negative, that is:
dG < 0
We can calculate dG using:
dG = dH - dS
When we plug in the given values, we see that the sign of dG will never be negative; therefore, the reaction will not be spontaneous under any conditions.
Answer: A=7 for the isotope with 4 neutrons.
Explanation:A lithium atom contains 3 protons in its nucleus. Notice that because the lithium atom always has 3 protons, the atomic number for lithium is always Z = 3. The mass number, however, is A = 6 for the isotope with 3 neutrons, and A = 7 for the isotope with 4 neutrons.
Answer: The answer is 6.78 grams.
Explanation: The equation used for solving this type of problems is:
where, 
is the initial amount of radioactive substance, N is the remaining amount and n is the number of half lives.
Number of half lives is calculated on dividing the given time by the half life.
n = time/half life
Time is given as 48.0 hours and the half life is given as 4.536 days. let's make the units same and for this let's convert the half life from days to hours.
= 108.864 hours
So, 
= 0.441
Since 5.00 g is the required amount when the radioactive substance is delivered to the scientist, it would be the final amount that is N. We need to calculate the initial amount. Let's plug in the values in the equation:
= 6.78 g
So, 6.78 g of the radioactive substance needs to be ordered.
