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givi [52]
3 years ago
14

Which of these statements about half-life is true? Check all that apply. Half-lives vary dramatically from isotope to isotope. A

relationship exists between isotopes and half-lives. Half-lives are constant for a particular isotope. Half-life is an exact measure of when individual atoms will decay. Temperature, pressure, and density affect the half-life of an isotope.​
Chemistry
1 answer:
juin [17]3 years ago
7 0

Answer:A,C

Explanation:

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life will not be possible on earth without the water that covers much of its surface and the air that surrounds it earth water a
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3 years ago
Identify each energy exchange as primarily heat or work and determine whether the sign of ΔE is positive or negative for the sys
Semmy [17]

Answer:

a. Work, ΔE is negative;

b. Work, ΔE is negative;

c. Work, ΔE is positive.

Explanation:

In the three cases, there is energy exchange in primarily work. The heat is the energy flow because of the difference in temperature. Of course, some heat may be lost in the cases by dissipation.

In the letter <em>a</em> the system is at an initial velocity different from 0, and then it stops. The energy that is represented here is the kinetic energy, which is the energy of the movement. Note that the system goes from a higher velocity to 0, so it is losing kinetic energy, or work, so ΔE = Efinal - Einitial < 0.

In letter <em>b</em>, the system is falling from a certain high to the floor, so its gravitational potential energy is change. That potential energy represents the energy that gravity does when an object shifts vertically. Because it goes from a high to 0, the energy is been lost, so ΔE = Efinal - Einitial < 0.

In letter <em>c</em>, the system is going higher and with higher velocity, so there is a greatness in the gravitational potential energy and the kinetic energy, both works, so ΔE = Efinal - Einitial > 0.

8 0
4 years ago
The most probable mechanism of reactivity for the solvolysis of 2-chloro-norbornane is
velikii [3]

The rate determining step for the reactivity for the solvolysis of 2-chloro-norbornane depends only on the decomposition of a single molecular species which is the 2-chloro-norbornane itself. For unimolecular reactions, the mechanism pathway being followed is that of an SN1 mechanism.

 

Answer:

<span>SN1 mechanism</span>

5 0
4 years ago
Kindly tell me all the important things to remember about periodic table. Like, how it was made, it's history and other stuff. T
Molodets [167]
Remember that the:
1. Vertical columns are groups and families
2. Horizontal columns are periods
3. Period 1 has 2 e-, 2 has 8 e-, 3 has 8 e-, and 4 has 18 e-
3.The number on top of the groups/families shows what group it is on (ex. 1A, 2A, 3B, 4B, etc) and the number on top of that indicates the number of the same thing (what group it is)
                     ⇒ ex. 1A has 1 val e-. 2A has 2 val e-. 3A has 3 val e- ( and rest goes up until 8A). Note: I skipped the transitions metals since they don't have accurate amount of val e-.
4. Know which is the mass number, atomic number, symbol, or name.
5. Where the metals, non- metals, and metalloids are located.
6. Elements on the same groups have similar properties.
7. The first group is Akali Metals and are very unstable and very reactive
8. Second group is Akaline Earth Metals 
9. The middle, groups 3-12 are Transition Metal
10. Group 13 is the Boron Family.
11. Group 14 is the Carbon Family
12. Group 15 is the Nitrogen Family
13. Group 16 is the Oxygen Family.
14. Group 17 is the Halogen, salt families
15. Group 18 is the Noble Gases, and are very stable and not reactive. 
I hope this helps. :)
7 0
3 years ago
3. Suggest . how to do an experiment to find the solubility of salt​
slamgirl [31]
You can put salt in water and record how long that takes the water to dissolve. And then have just water in a cup and see how long it takes the water ti dissolve compared to the salt water.
8 0
3 years ago
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