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3 years ago

An atom of lithium 7 has an equal number of

Chemistry

2 answers:

Andreas93 [3]3 years ago

8 0

Electrons and protons
yw

lukranit [14]3 years ago

5 0

Electrons and protons because they are essentially always the same

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Which biome contains mostly coniferous trees and receives 35 to 100 cm of rain per year? deciduous forest taiga (boreal forest)

Sever21 [200]

option B, taiga (boreal forest).

(hope this helps ^^)

8 0

2 years ago

Read 2 more answers

The half-life of radium-226 is 1590 years. if a sample contains 100 mg, how many mg will remain after 1000 years?

Katyanochek1 [597]

Answer:

$a=64.7mg$

Explanation:

Hello,

In this case, we need to remember that for the required time for a radioactive nuclide as radium-226 to decrease to one half its initial amount we are talking about its half-life. Furthermore, the amount of remaining radioactive material as a function of the half-lives is computed as follows:

$a=a_0(\frac{1}{2} )^{\frac{t}{t_{1/2}} }$

Therefore, for an initial amount of 100 mg with a half-life of 1590 years, after 1000 years, we have:

$a=100mg(\frac{1}{2} )^{\frac{1000years}{1590years} }\\\\a=64.7mg$

Best regards.

4 0

3 years ago

How many moless is 4.91x10^22 molecules of H3PO4?

Lynna [10]

1 mol = 6.023x10^23 number of molecules (Avogadro's number)

1 : 6.023x10^23
X : 4.91x10^22

(6.023x10^23)X = 4.91x10^22

X = 4.91x10^22/6.023x10^23

X = 0.082 Moles

6 0

3 years ago

The girl in the picture is at the highest point in swinging and starts to come down. Which statement could describe the changes

vredina [299]

Answer:

1.(A) 2.(A) 3.(C) 4.(D)

Explanation:

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3 years ago

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A material has an ASTM grain size number of 7. Determine the magnification, if the number of grains per square inch observed is:

Luden [163]

Answer:

A) M = 100X

B) M = 36X

C) M = 178.88X

Explanation:

Given data:

ASTM grain size number 7

a) total grain per inch^2 - 64 grain/inch^2

we know that number of grain per square inch is given as

$Nm = 2^{n-1} (\frac{100}{M})^2$

where M is magnification, n is grain size

therefore we have

$64 = 2^{7-1}(\frac{100}{M})^2$

solving for M we get

M = 100 X

B) total grain per inch^2 = 500 grain/inch^2

we know that number of grain per square inch is given as

$Nm = 2^{n-1} (\frac{100}{M})^2$

where M is magnification, n is grain size

therefore we have $500 = 2^{7-1}(\frac{100}{M})^2$

solving for M we get

M = 36 X

C) Total grain per inch^2 = 20 grain/inch^2

we know that number of grain per square inch is given as

$Nm = 2^{n-1} (\frac{100}{M})^2$

where M is magnification, n is grain size

therefore we have $20 = 2^{7-1}(\frac{100}{M})^2$

solving for M we get

M = 178.88 X

8 0

2 years ago