The half life of a substance is the time taken by a radioactive substance to decay by half its original mass. In this case, the half life of Potassium-40 is 1.3 billion years.
Original mass of Potassium-40 = 12 g (100%)
New mass after the decay = 3 g ( 25 %, since 75% was replaced by argon)
New mass = Original mass × (1/2)^n ; where n is the number of half lives.
3 = 12 × (1/2)^n
(1/2)^n = 1/4
n = 2
Therefore; the time taken will be 1.3 × 2 = 2.6 Billion years
I also think it’s B but not quite sure
Answer:
Mantle convection
Explanation:
The source of the force that moves tectonic plates along plate boundaries is as a result of the mantle convection.
- Heat energy produced in the mantle especially from radioactive decay is a very important source of internal heat that drives plate motion.
- Denser and cold materials close to the over-riding lithosphere above sinks deep into the mantle.
- Hotter and lighter materials rises to the surface.
- This sets up a convection cell by which the plates above are driven.
The problem ask to calculate the value of x if an iron taht has a mass of 21.5g and has an initial temperature of 1000.0C is submerge in Xg of a water at 20C. So the value of X is letter C. 132 g. I hope you are satisfied with my answer and feel free to ask for more
Answer:
2 moles of Sn are produced when 4 moles of H2(g) are consumed completely
Explanation:
to determine the number of moles of sn (l) produced when 4.0 moles of H2 (g) is consumed completely.
First, find the number of moles of H2 consumed by taking this as limiting reagent.
Then find the moles of Sn (l) taking into account the stoichiometric relationship between H2(g) and Sn(l). 2:1
(s) + 2
(g) ⇒ Sn(l) + 2
(g)
∴2 moles of Sn are produced when 4 moles of H2(g) are consumed completely.
