Answer:
Mass of Rb-87 is 86.913 amu.
Explanation:
Given data:
Average mass of rubidium = 85.4678 amu
Mass of Rb-85 = 84.9117
Ratio of 85Rb/87Rb in natural rubidium = 2.591
Mass of Rb = ?
Solution:
The ration of both isotope is 2.591 to 1. Which means that for 2.591 atoms of Rb-85 there is one Rb-87.
For 100% naturally occurring Rb = 2.591 + 1 = 3.591
% abundance of Rb-85 = 2.591/ 3.591 = 0.722
% abundance of Rb-87 = 1 - 0.722= 0.278
84.9117 × 0.722 + X × 0.278 = 85.4678
61.306 + X × 0.278 = 85.4678
X × 0.278 = 85.4678 - 61.306
X × 0.278 = 24.1618
X = 24.1618 / 0.278
X = 86.913 amu
Answer:
Answer is 2nd
Explanation:
some energy is transformed into mass
Answer:
<u><em>Pangaea</em></u>
<u><em>Alfred Wegner</em></u>
<u><em>plate tectonics</em></u>
Explanation:
What did Earth look like 250 million years ago? The continents of Earth were clustered together in formation that a scientist named<em> </em><u>Pangaea</u><u><em>.</em></u>The scientist that named "Pangaea" was a German scientist by the name of <u>Alfred Wegner.</u> He theorized that "Pangaea" split apart and the different landmasses, or continents, drifted to their current locations on the globe. Wegener's theories of plate movement became the basis for the development of the theory of <u>plate tectonics.</u>
"Saltation" which is the movement of hard particles such as sand over an uneven surface in a turbulent flow of air or water.
Answer:
0.055g/mL
Explanation:
Data obtained from the question include:
Molar Mass of the gass sample = 71g/mol
Volume of the gas sample = 1300 mL
Density =?
The density of a substance is simply mass per unit volume. It is represented mathematically as:
Density = Mass /volume.
With the above equation, we can easily obtain the density of sample of gas as illustrated below:
Density = 71g / 1300 mL
Density = 0.055g/mL
Therefore, the density of the gas sample is 0.055g/mL