Answer: A
Explanation:
This means that the atomic number decreases by 1 but the mass remains constant, meaning the atomic number of the new element is 20. This corresponds to calcium.
Answer: This is true.
Explanation:
It is true because if becomes frozen, then it is physically harder to melt...
T=20 min
m₀=200 g
t=60 min
the mass of element through time t is:
m=m₀*2^(-t/T)
m=200*2^(-60/20)=25 g
25 grams of element will be left after 60 minutes
