an atom that has 18 protons, 18 neutrons and 20 neutrons. This atom has mass number of 38
mass number is calculated as number of protons + number on neutrons
therefore the mass number of the atom = 18+20= 38
Since the atom has a electronic configuration of 2.8.8,the atom cannot be negatively or positively charged because it is stable.
The atomic number of the atom is 18 since atomic number is equal to number of protons
Answer:
Bubbles are comprised of gases, which have a lesser density than water. Since they are less dense, they get pushed up to the surface, and they rise, lighter than the liquid around them. This is just like helium in air; helium is lighter than air, so it rises, pushed to the top by the pressure around it.
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Answer: The rate constant for the reaction is 
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = age of sample = 559 min
a = let initial amount of the reactant = 
a - x = amount left after decay process = 



The rate constant for the reaction is 
Mass number = protons + neutrons. 12 + 11 = 23.
Ookay
1) T
2) T
3) F
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