The half-life of cobalt-60 is 5.26 years. After 10.52 years, 5 grams of a 20-gram sample will remain is TRUE
<u>Explanation:</u>
Mass of cobalt = 20 g
Half-life = 5.26 years
Mass remains after 10.52 years = 5 g
This can be solved by using given below formula, 
= initial mass
t = number of years from when the mass was m_0
m(t) = remaining mass after t years
Number of half-lives = 
Number of half-lives = 
Number of half-lives = 2
At time zero = 20 g
At first half-life = 
= 10 g
At second half life = 
= 5 g
The given statement is true.
Answer:
The net ionic equation is
C6H5COOH+ CN-= C6H5COO- + HCN
Explanation:
From the ionic equation
C6H5COOH + Na+ + CN- = C6H5COO- + Na+ + HCN
Only sodium is the spectator ion, so it cancels out, since C6H5COOH and HCN do not ionize completely they are left undissociated
Answer:
If anything but H2O were found, it would be evidence of a chemical change. Therefore, 4 is the only viable evidence that it was a physical change of H2O liquid to H2O gas.
Answer:
when the rates of the forward and reverse reactions are equal
Explanation:
In a chemical system, the reaction reaches a dynamic equilibrium when the rate of formation of product equals the rate of formation of reactants. This implies that both the forward and revered(backwards) reaction are occurring at the same rate.
