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enot [183]
2 years ago
10

What is the mass number of an isotope with an atomic number of 57 and that has 69 neutrons?

Chemistry
1 answer:
Karolina [17]2 years ago
7 0

Answer:

mass number=126

Explanation:

57+69=126

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Why is the brcl molecule polar? the shared electrons are closer to cl due to the greater electronegativity of chlorine. bromine
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The shared electrons are closer to Cl due to the greater electronegativity of chlorine.
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A Compound Contains Two or more _______. 
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A compound contains two or more elements chemically combined

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HELP 20 POINTS <br>A photon has a wavelength of 366 nm. What is the frequency of this photon?​
den301095 [7]

Answer:

9.  8.2x10¹⁴ Hz

Explanation:

Wavelength λ = 366 nm

Formula: Frequency = C / λ

To find the wavelength in m,

1 nm = 1.0x10⁻⁹ m

So, 366 nm = ?

= 3.66x10⁻⁷ m

Frequency = 3.0x10⁸m.s-1 / 3.66x10⁻⁷ m

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8 0
3 years ago
Find the percent composition of each element in KMnO4
VARVARA [1.3K]
The way you want to find the percent composition would be by breaking down the problem like so:

K= atomic mass of K which is 39.098
Mn = atomic mass of Mn which is 54.938
O= atomic mass of o which is 15.999

Then you want to add 39.098+ 54.938+ 15.999 and you get 110.035 which is the molar mass for KMnO

Then you want to take each molar mass and then divide it 110.035 and multiply by 100

Ex. K = 39.098/ 110.035 and the multiply what you get by a 100

You do this for the other elements as well good luck!


6 0
3 years ago
What is the mass of CO2 lost at 20 min from the limestone sample?
harkovskaia [24]

Answer:

The mass, CO2 and CO3 from the limestone sample is discussed below in details.

Explanation:

(A) mass loss of sample of limestone after 20 min

= 0.8437g-0.5979g = 0.2458 g

From the given reaction of limestone, 2 mol of the sample gives 2 moles of CO 2.

Therefore  

184.4 g ( molar mass of limestone) gives2× 44 g of carbon dioxide.

1 g of sample gives 88/184.4 g of carbon dioxide

Hence 0.2458 g sample gives

= 88/184.4 × 0.2458 g = 0.117 g carbon dioxide

(B) mole of CO 2 lost = weight/ molar mass

= 0.117 g / 44 g/mol =0.0027 mole

(C). 1 mol of limestone contain 2 mol of carbonate ion

From the reaction we know that carbonate ion of limestone is converted into carbondioxide

Hence lost carbonate ion = 0.2458 g

(D) we know that

1 mol limestone contain 1mol CaCO​​​ 3

Hence in sample present CaCO​​​ 3

= 1mole / 184.4 g × 0.8437 g= 0.00458 mol CaCO​​​3

8 0
3 years ago
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