Fluorine 20 (F - Atomic number 9 and atomic mass 20). Firstly we need to know what is beta decay. Beta decay occurs when one neutron changes into a proton and an electron therefore the atomic mass will remain the same as even though we loose a neutron it is replaced by a proton, the atomic number is always raised by 1 when one beta decay occurs. The produced electron is shot out of the nucleus at an incredible speed. This speedy electron we call a beta particle.
Ok now the reaction.
20 20 0
F -> Ne + e
9 10 -1
Remember the atomic number determines the nature of the element ( i.e what elemnt it is).
Hope this helps :).
Sodium, hydrogen, carbon, and oxygen
They are in order according to their atomic number, so the position should tell you the atomic number.
Answer:
v = 658.82 km/h
Explanation:
The distance between New York and London is 
Time taken from New York to London is 8.5 hours
We need to find the average speed of the plane.
Total distance covered divided by the total time taken is equal to the average speed of an object. So,

So, the average speed of the plane is 658.82 km/h.
Answer:
exothermic reaction
Explanation:
If there is a drop in temperature, then energy was lost to the surroundings because temperature is the average measure of kinetic energy. An exothermic reaction would result in this lost of energy. An endothermic reaction would absorb energy and make the temperature rise.