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3 years ago

How many Mg atoms are present in 170g of Mg

1 answer:

8 0

In order to calculate the number of atoms, we must first know the number of moles present. And
moles = (mass present) / (molecular mass)
Therefore, the moles of Mg present are
170 / 24 = 7.08
The number of atoms in a mole of substance is given by Avagadro's Number which is 6.02 x 10^23
Since there are 7.08 moles, there are:
7.08 * 6.02*10^23
= 4.26 * 10^24 atoms

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How long would it take a train to travel 500 miles at 25 mph?

faust18 [17]

Answer:

2 or 3 hrs

I think

<h2>HOPE IT HELPED </h2>

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3 years ago

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λmax for the π → π* transition in ethylene is 170 nm. Is the HOMO-LUMO energy difference in ethylene greater than or less than t

-Dominant- [34]

Answer:

the HOMO-LUMO energy difference in ethylene is greater than that of cis,trans−1,3−cyclooctadiene

Explanation:

The λmax is the wavelength of maximum absorption. We could use it to calculate the HOMO-LUMO energy difference as follows:

For ethylene

E= hc/λ= 6.63×10^-34×3×10^8/170×10^-9= 1.17×10^-18J

For cis,trans−1,3−cyclooctadiene

E= hc/λ=6.63×10^-34×3×10^8/230×10^-9=8.6×10^-19J

Therefore, the HOMO-LUMO energy difference in ethylene is greater than that of cis,trans−1,3−cyclooctadiene

8 0

3 years ago

Assume a hydrogen atom has an electron in the n-level corresponding to the month of your birthday (jan = 1, feb = 2, etc.) calcu

luda_lava [24]

My Birthday is in April, So, electron of H atom is in n=4( pfund series).

Ionisation Energy= +13.6(z^2/n^2)
= +13.6(1/16)
= +0.85 eV

6 0

3 years ago

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815 yd to km (need 3 sig fig)

SpyIntel [72]

<u>Answer:</u> The correct answer is 0.745 km

<u>Explanation:</u>

We are given:

A numerical value of 815 yards

To convert this into kilometers, we use the conversion factor:

1 km = 1093.6 yards

Converting the given value into kilometers, we get:

$\Rightarrow 815yd\times \frac{1km}{1093.6yd}=0.745km$

Hence, the correct answer is 0.745 km

5 0

3 years ago

What is the concentration of each ion in 15.00 ml of a 7.85 X 10^-6 M solution of Tc3 (PO4)7?

Daniel [21]

Answer:

Tc^(+7) - 2.35*10^-5M

PO4(^-3) - 5.50*10^-5M

Explanation:

Tc3(PO4)7 <---> $3Tc^{7+} + 7PO_{4}^{3-}$

1 mol 3 mol 7 mol

7.85 X 10^-6 M 3*7.85*10^-6M 7*7.85*10^-6M

2.35*10^-5M 5.50*10^-5M

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3 years ago