<span>A beryllium atom has 4 electrons.
1, 0, 0, +1/2
1, 0, 0, -1/2
2, 0, 0, +1/2
2, 0, 0, -1/2</span>
Element with an atomic number of 58 is actually Cerium, so the symbol should be Ce, not Co because that is Cobalt which has an atomic number of 27. With that being said, the notation for isotopes is the symbol of the element with a superscript and a subscript that are aligned. The superscript represents the mass number.
Mass number = protons + neutrons = 58 + 33 = 91
The subscript is the atomic number which is 58. The notation is written in the picture attached.
102 grams.
Equation:
Quantify of heat = mass x specific heat x difference in temperature
We have: quantity of heat : 2300J
specific heat: .449 J/g
difference in t: 80 - 30 = 50
Solve for mass: 2300 = mass x 0.449 x 50
mass = 102.449
2 sig-figs --> 102 grams
Incomplete question. However, I provided a specific example of stewardship of the atmosphere.
<u>Explanation:</u>
First, note that the term stewardship refers to the belief that humans are obligated to take care and look after our environment (which includes the atmosphere.
An example of this is: deciding to change our mode of transportation: What this entails is that we may decide to switch to riding a bicycle to places rather than going by car. By so doing you will be reducing the number of greenhouse gases emitted into the environment as bicycles do not emit harmful gases when used.
Answer:

Explanation:
Mass of one tablet = 20 mg
Mass of two tablets = 
Percent that is soluble in water = 40%
Mass of tablet that is soluble in water = 
So, mass of solute is 
Density of water = 1 kg/L
Volume of water = 1 L
So, mass of 1 L of water is 
PPM is given by

Hence, the concentration of iodine in the treated water
.