Answer:
Law of Conservation of Energy
Explanation:
<u>Answer:</u>
<u>For a:</u> The isotopic representation of iodine is 
<u>For b:</u> The isotopic representation of cesium is 
<u>For c:</u> The isotopic representation of strontium is 
<u>Explanation:</u>
The isotopic representation of an atom is: 
where,
Z = Atomic number of the atom
A = Mass number of the atom
X = Symbol of the atom
We are given:
Number of neutrons = 78
Atomic number of iodine = 53 = Number of protons
Mass number = 53 + 78 = 131
Thus, the isotopic representation of iodine is 
We are given:
Number of neutrons = 82
Atomic number of cesium = 55 = Number of protons
Mass number = 55 + 82 = 137
Thus, the isotopic representation of cesium is 
We are given:
Number of neutrons = 52
Atomic number of strontium = 38 = Number of protons
Mass number = 38 + 52 = 90
Thus, the isotopic representation of strontium is 
Answer:

Explanation:
We want to convert from moles to grams, so we must use the molar mass.
<h3>1. Molar Mass</h3>
The molar mass is the mass of 1 mole of a substance. It is the same as the atomic masses on the Periodic Table, but the units are grams per mole (g/mol) instead of atomic mass units (amu).
We are given the compound PI₃ or phosphorus triiodide. Look up the molar masses of the individual elements.
- Phosphorus (P): 30.973762 g/mol
- Iodine (I): 126.9045 g/mol
Note that there is a subscript of 3 after the I in the formula. This means there are 3 moles of iodine in 1 mole of the compound PI₃. We should multiply iodine's molar mass by 3, then add phosphorus's molar mass.
- I₃: 126.9045 * 3=380.7135 g/mol
- PI₃: 30.973762 + 380.7135 = 411.687262 g/mol
<h3>2. Convert Moles to Grams</h3>
Use the molar mass as a ratio.

We want to convert 3.14 moles to grams, so we multiply by that value.

The units of moles of PI₃ cancel.


<h3>3. Round</h3>
The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated, that is the tens place.
The 2 in the ones place tells us to leave the 9.

3.14 moles of phosphorous triiodide is approximately equal to <u>1290 grams of phosphorus triodide.</u>
Answer:
V = 34430 mL
Explanation:
Given data:
Volume in mL = ?
Number of moles of gas = 2.00 mol
Temperature = 36°C (36+273= 309K)
Pressure of gas = 1120 torr
Solution:
Formula:
PV = nRT
V = nRT/P
V = 2.00 mol ×62.4 torr • L/mol · K × 309K / 1120 torr
V = 38563.2 torr • L / 1120 torr
V = 34.43 L
L to mL
34.43 L ×1000 mL / 1 L
34430 mL
Answer:
This would be the hydride ion where H gains an electron from a metal such as Na
Explanation: