<u>Answer:</u> Silver has 47 electrons, 47 protons and 43 neutrons. Barium has 56 electrons, 56 protons and 76 neutrons.
<u>Explanation:</u>
Atomic number is defined as the number of protons or electrons that are present in a neutral atom.
Atomic number = number of protons = number of electrons
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
Atomic number = 47
Mass number = 90
Atomic number = Number of protons = Number of electrons = 47
Number of neutrons = Mass number - Atomic number = 90 - 47 = 43
Hence, silver has 47 electrons, 47 protons and 43 neutrons.
Atomic number = 56
Mass number = 132
Atomic number = Number of protons = Number of electrons = 56
Number of neutrons = Mass number - Atomic number = 132 - 56 = 76
Hence, barium has 56 electrons, 56 protons and 76 neutrons.
The answer would be C) Observe and ask questions because if we do process of elimination we see that drawing conclusions is NOT the first step, forming a hypothesis and illustrating the process is part of the method, but NOT the first step.
Explanation:
1) Initial mass of the Cesium-137=
= 180 mg
Mass of Cesium after time t = N
Formula used :
Half life of the cesium-137 = ![t_{1/2}=30 years[p/tex]where, [tex]N_o](https://tex.z-dn.net/?f=t_%7B1%2F2%7D%3D30%20years%5Bp%2Ftex%5D%3C%2Fp%3E%3Cp%3Ewhere%2C%0A%3C%2Fp%3E%3Cp%3E%5Btex%5DN_o)
= initial mass of isotope
N = mass of the parent isotope left after the time, (t)
= half life of the isotope
= rate constant
Now put all the given values in this formula, we get
Mass that remains after t years.
Therefore, the parent isotope remain after one half life will be, 100 grams.
2)
t = 70 years
N = 35.73 mg
35.73 mg of cesium-137 will remain after 70 years.
3)
N = 1 mg
t = ?
t = 224.80 years ≈ 225 years
After 225 years only 1 mg of cesium-137 will remain.
That answer is either 3 or 4, but I truly forgot which of the two.
