it represents a physical change. it is not a chemical change because its chemical formula does not change unless combustion is involved.
Answer:
12
Explanation:
23-11, why?, because, the difference between atomic and mass number is the neutron number which most a times is equivalent to the electron number.
Answer:
The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.
Explanation:
Pressure in the container is P and volume is V.
Temperature of the helium gas molecules =
Molecules helium gas = x
Moles of helium has = 
PV = nRT (Ideal gas equation)
...[1]
After removal of helium gas only a fourth of the gas molecules remains and pressure in the container and volume should remain same.
Molecules of helium left after removal = 
Moles of helium has left after removal = 
...[2]




The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.
Answer:
None of the alpha particles fired at the foil are being repelled back, like they were in the Rutherford atom simulation.I hope this is correct.