T = half life period of decay for atoms of element A = 20,000 years
N₀ = initial number of atoms of element A = 10,000 atoms
N = final number of atoms after time "t" = 2500 atoms
t = time of decay = ?
λ = decay constant = ?
decay constant is given as
λ = 0.693/T
λ = 0.693/20,000
λ = 0.00003465 years⁻¹
atoms after decay for time "t" is given as
N = N₀ 
inserting the values
2500 = (10000) 
t = 40,000 years
so correct choice is
B) 40,000 years
This should help,
Search up the Scientific method and lookup for the meaning of each word.
I can't help with all of it but this should help for most
So the question is asking for time.
Time= distance / speed
120/30
4
Therefore answer is d
Answer:
I believe it would be Pennsylvania and New Jersey they both border Maryland. Didn't see any other states that border Maryland with West Virginia and Virginia being exempt from the question.
Explanation:
The coolant gas in a fridge takes heat from the fridge and "pumps" or "dumps" it in the outside. The back of a working fridge is usually quite warm, and one source of that heat is the contents of the fridge.
Electrical energy is used to pump the coolant round the various components of the fridge's cooling system. It also possibly powers any lights in the fridge. That funny whirring sound may well be a motor, and motors are driven by electrical energy. If your power goes off, then your fridge stops fridging. all the stuff in the fridge warms up to room temp slowly, and you may end up with some "too warm" grub.
