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EleoNora [17]
2 years ago
7

Please help! it’s due date is in a few minutes

Chemistry
1 answer:
Licemer1 [7]2 years ago
7 0

Answer:

40'0'

Explanation:

X is smaller than |-40|

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HELP ILL MARK BRAINLIEST
exis [7]

Answer:

Formation. Main-sequence stars, including the sun, form from clouds of dust and gas drawn together by gravity. ... The core that is left behind will be a white dwarf, a husk of a star in which no hydrogen fusion occurs. Smaller stars, such as red dwarfs, don't make it to the red giant state.

Explanation:

4 0
3 years ago
What assumptions do we make in order to use the Henderson-Hasselbalch equation? a. Both the weak acid and its conjugate base are
zepelin [54]

Answer:

The final and initial concentration of the acid and it's conjugate base are approximately equal, that is we use the weak acid approximation.

Explanation:

The Henderson-Hasselbalch is used to calculate the pH of a buffer solution. It depends on the weak acid approximation.

Since the weak acid ionizes only to a small extent, then we can say that [HA] ≈ [HA]i

Where [HA] = final concentration of the acid and [HA]i = initial concentration of the acid.

It also follows that [A^-] ≈ [A^-]i where [A^-] and[A^-]i refer to final and initial concentrations of the conjugate base hence the answer above.

7 0
3 years ago
What material causes a wave to bounce off of it
Harrizon [31]
Its a Reflector

Reflector is some sort of material that is used to collect or bounce off energy such as sound, light, or radio wave

Usually it took form in some sort of parabolic that revolve around an axis
8 0
3 years ago
Read 2 more answers
Phase or state of matter​
klio [65]

Answer:

state of mater

Explanation:

6 0
3 years ago
A rock contains 0.623 mg of 206Pb for every 1.000 mg of 238U present. Assuming that no lead was originally present, that all the
maxonik [38]

Answer:

t = 3,496x10⁹ years

Explanation:

The decay of ²³⁸U is:

²³⁸U → ²⁰⁶Pb + 8He + 6e⁻

Moles of ²⁰⁶Pb presents in 0,623mg are:

0,623x10⁻³g×(1mol / 206g) = 3,02x10⁻⁶ moles of ²⁰⁶Pb.

These moles are equals to moles of ²³⁸U before decay, that means, 3,02x10⁻⁶ moles²³⁸U

In grams:

3,02x10⁻⁶ moles²³⁸U× (238g / 1mol) = 7,20x10⁻⁴ g ²³⁸U = 0,720 mg²³⁸U

That means initial ²³⁸U was 1,000mg + 0,720mg =<em> 1,720mg</em>

Applying the formula:

ln (N₀/N) t₁₂ = t ln2

Where N₀ is initial amount of uranium (1,720mg), N is concentration of uranium (1,000mg),  half-life time is a constant (t₁₂= 4,468x10⁹ years) and t is the time transcurred for the reaction. Replacing:

ln(1,720/1)*4,468x10⁹ years = t ln2

<em>t = 3,496x10⁹ years</em>

<em></em>

I hope it helps!

6 0
3 years ago
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