Answer:
13 years
Explanation:
From;
0.693/t1/2 = 2.303/t log (No/N)
Where;
t1/12 = half-life of Cobalt-60 = 5.3 years
t = time taken = the unknown
No = mass of radioactive material originally present = 5.2 g
N = mass of radioactive material at time t = 0.95 g
Substituting values;
0.693/5.3 = 2.303/t log (5.2/0.95)
0.131 = 2.303/t(0.738)
0.131 = 1.6996/t
t = 1.6996/0.131
t = 12.97 years
t = 13 years(to the nearest whole number)
Answer:
3.01×10²³ atoms of calcium
Explanation:
number of moles = number of atoms/Avogadro's constant
n = N/NA
N = n×NA = 0.500 mol×6.02×10²³ mol^-1
N = 3.01×10²³ atoms of calcium
Answer:
Ice cubes with salt melt faster. When you add salt, it dissolves in the water of the ice cube. The freezing temperature of salt water is 32 degrees Fahrenheit lower than that of fresh water.
