Answer: ice is less dense than liquid water. If ice was more dense, Earth would freeze.
Explanation: There are many reasons why life on Earth depends on the characteristics of water. One could discuss hydrogen bonds and its role as a solvent, but the unusual property of water is is the change in density with change in temperature. Water is densest at 4 degC, which is why ice floats - it is less dense than cold water (it melts quickly in warm water, so density isn’t impotant at higher temperatures). Most liquids are less dense than the solid, frozen form. If this was the case with water, any ice that formed would sink, and sease would freeze from the bottom up. Furthermore, the lowest layers would be insulated and would not all melt in summer. Thus over time, the seas would become a thin layer of liquid water at best, over solid ice. Life could not develop without liquid seas. In addition, ice is reflective, reducing the amount of sunlight absorbed, further reducing temperatures. Without ocean circulation, polar areas would be even colder, and there would be no rain.
Answer:
35.8 u
Explanation:
The atomic mass of Cl is the weighted average of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its percent abundance).
Atomic mass of Cl-35 = 17p + 18n = 17 × 1.007 u + 18 × 1.009 u
= 17.119 u + 18.162 u = 35.28 u
Atomic mass of Cl-37 = 17p + 20n = 17 × 1.007 u + 20 × 1.009 u
= 17.119 u + 20.180 u = 37.30 u
Set up a table for easy calculation.
0.755 × 35.28 u = 26.64 u
0.245 × 37.30 u = 9.138 u
TOTAL = 35.8 u
Note: The actual atomic mass of Cl is 35.45 u.
The calculated value above is incorrect because
(a) the given isotopic percentages are incorrect and
(b) the protons and neutrons have less mass when they are in the nucleus than when they are free. Thus, the calculated masses of Cl-35 and Cl-37 are too high.
1016)(2.2<span> × </span>1010<span>) = A × </span>10B<span> A= B= Chemistry.</span>
Correct Answer: Option C
Reason:
<span>The </span>Pauli Exclusion Principle<span> states as '<em>in an atom or molecule, no two electrons can have the same four electronic quantum numbers. Further, an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.</em>'
</span>
Thus, it can be seen that in option C, electrons in last 2 subshell have electrons with same spin, which is a violation of Pauli Exclusion Principle .
