Answer:
The answer to your question is: 16.7 g of KBr
Explanation:
Data
mass KBr = ? g
Volume = 0.400 L
Concentration = 0.350 M
Formula
Molarity = moles / volume
moles = molarity x volume
Process
moles = (0.350)(0.400)
= 0.14
MW KBr = 39 + 80 = 119 g
119 g of KBr -------------------- 1 mol
x -------------------- 0.14 mol
x = (0.14 x 119) / 1
x = 16.7 g of KBr
physical change
particles retain there composition and identity
there is no change in there chemical properties of the substance
the chemical changes should be the other two.
If it is wrong I'm truly sorry.
Continental drift is the movement of Earth’s continents over long periods of time. An evidence for this is that some continents look like puzzle pieces that can fit together, such as South America and Africa. Another evidence is that fossils of the same type have been found in different continents, far apart - suggesting that the two continents once were joined. Another evidence is that identical rocks were found at both sides of the Atlantic Ocean by Alfred Wegener, the main developer of the continents drift theory.
Positron emission = emission of a positron and a neutrino when a proton is convert into a neutron. The total number of particles in the nucleus doesn't change, -1 proton +1 neutron
It's a spontaneous reaction for some nucleus.
eg:
Positron = e+
Neutrino=ve
O-15 --> N-15 + e+ +ve
Electron capture= A nucleus absorb an electron while a proton is convert in a neutron and emit a neutrino. The total number of particles in the nucleus doesn't change, -1 proton +1 neutron
eg:
Al-26 +e- --> Mg-26 + ve
Electron capture and positron emission are two mechanisms to explain the decay of some unstable isotopes. Electron capture is usually observed when the energy difference between the initial and final state is low. Mainly because of the larger amount of kinetic energy need for the expulsion of two particles with the positron emission mechanism.
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