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ICE Princess25 [194]
3 years ago
13

Which statement is true about Atoms

Chemistry
1 answer:
ankoles [38]3 years ago
6 0

They have protons that are identical...

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A sample that weighs 103.75 g is a mixture of 30% helium atoms and 70% krypton atoms. How many particles are present in the samp
aalyn [17]
1) we calculate the molar mass of He (helium) and Kr (Krypton).
atomic mass (He)=4 u
atomic mas (Kr)=83.8 u

Therefore the molar mass will be:
molar mass(He)=4 g/mol
molar mass(Kr)=83.8 g/mol.

1) We can find  the next equation:
mass=molar mass  x number of moles.

x=number of moles of helium
y=number of moles of helium. 

(4 g/mol) x  +(83.8 g/mol)y=103.75 g
Therefore, we have the next equation:

(1)

4x+83.8y=103.75


2) We can find other equation:

We have 30% helium atoms and 70% Kryptum atoms, therefore we have 30% Helium moles and 70% of Krypton moles.

1 mol  is always 6.022 * 10²³ atoms or molecules, (in this case atoms).

Then:
x=number of moles of helium
y=number of moles of helium.
(x+y)=number of moles of our sample.

x=30% of (x+y)

Therefore, we have this other equation:
(2)

x=0.3(x+y)


With the equations(1) and (2), we have the next system of equations:

4x+83.8y=103.75

x=0.3(x+y)  ⇒ x=0.3x+0.3y  ⇒    x-0.3x=0.3y  ⇒ 0.7 x=0.3y ⇒ x=0.3y/0.7
⇒x=3y/7

We solve this system of equations by substitution method.
x=3y/7

4(3y/7)+83.8y=103.75
lower common multiple)7
12y+586.6y=726.25
598.6y=726.25
y=1.21

x=3y/7=3(1.21)/7=0.52

We have 0.52 moles of  helium and 1.21 moles of Krypton.

1 mol=6.022 * 10²³ atoms

Total number of particles=(6.022 *10²³ atoms /1 mol) (number of moles of He+ number of moles of Kr).

Total number of particles=6.022 * 10²³ (0.52+1.21)=6.022 * 10²³ (1.73)=
=1.044 * 10²⁴ atoms.

Answer: The sample have 1.044 * 10²⁴ atoms.
6 0
4 years ago
Read 2 more answers
(b) Ozone absorbs radiation of wavelengths 2200–2900 Å, thus protecting organisms from this radiation. Find the frequency and en
GrogVix [38]

The frequency and energy of most energetic of these photons is1.36*10^{15} Hz and 9.04*10^{-19} J respectively.

The high energy photons will have least wavelength. Taking the given less wavelength for calculation of frequency and energy of photons.

λ = 2200  Å

Also, we know, 1 Å = 10^{-10} m

So, λ = 2200*10^{-10}

λ = 2.2*10^{-7}<em> </em>m

Now, calculating frequency using the formula -

c = fλ, where c is speed of light, f is frequency and λ is wavelength.

We know, c = 3*10^{8} m/s

f = c/λ

f = \frac{3*10^{8} }{2.2*10^{-7} }

frequency = 1.36*10^{15} Hz

Now, calculating Energy through the formula -

E = hf, where E is energy, h is planck's constant and f is frequency

Value of planck's constant = 6.63*10^{-34} Js

E = 6.63*10^{-34}*1.36*10^{15}

Energy = 9.04*10^{-19} J

Thus, frequency and energy of photons is 1.36*10^{15} Hz and 9.04*10^{-19} J respectively.

Learn more about energy of photon -

brainly.com/question/15946945

#SPJ4

3 0
1 year ago
Why do people mix up weather and climate?
Marianna [84]

Answer:

The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time.

Explanation:

please mark this answer as brainlest

8 0
3 years ago
Read 2 more answers
Convert 20 cals to J
zimovet [89]

Answer: 83.68 J

Explanation:

1 cal=4.184 J

1×20=4.184×20

20cals=83.68 J

8 0
3 years ago
To determine the specific heat capacity of copper, Alyssa performed an investigation by which she dropped a heated piece of copp
user100 [1]

Answer:

0.446

Explanation:

ccu =  3035.655 / 104 g x (98.9 - 33.5)  = 0.446 J / g 0 C

6 0
2 years ago
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