An original sample of K-40 has a mass of 25.00 grams.
After 3.9 m 109 years, 3.125 grams of the original sample remains unchanged.
What is the half-life of K-40?
First step is to determine the remaining decimal amount.
3.125 grams /25.00 grams = 0.125
Second step is to determine the number of half lives.
(1/2)^n = 0.125
N log (1/2) = log 0.125
N = 3 years
Models are used to study atoms because we can't exactly study an atom with the naked eye, Using an enlarged model of an atom easier to study because we can pin point the different characteristics of the atom.
<span>Balancing the choices, we have as follows:
A. 3AgBr + GaPO4 → Ag3PO4 +GaBr3
B. 3H2SO4 + 2B(OH)3 → B2(SO4)3 + 6H2O
C. Fe + 2AgNO3 → Fe(NO3)2 + 2Ag
D. C2H4O2 +2O2 → 2CO2 + 2H2O
Therefore, the correct answers are option A and B. Hope this answers the question. Have a nice day.</span>
