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4 years ago

What does the Aufbau principle state?

2 answers:

8 0

Hello there!

The correct answer is B. Electrons will be added to an atom starting from the lowest possible level or sublevel.

Hope This Helps You!
Good Luck :)

Sidana [21]4 years ago

3 0

<u>Answer:</u> The correct answer is Option B.

<u>Explanation:</u>

Aufbau principle states that the electron will occupy the lowest energy level first before occupying the higher energy levels.

In filling of electrons, '1s' orbital will be filled first than '2s' orbital because the former has low energy level than the later.

For Example: Filling of electrons in chromium atom.

Chromium is the 24th element of the periodic table and its electronic configuration must be written as: $1s^22s^22p^63s^23p^63d^44s^2$

But the actual configuration for this is $1s^22s^22p^63s^23p^63d^54s^1$

This configuration is an exception to Aufbau's principle as half filled sub-levels is more stable than other configurations.

Hence, the correct answer is Option B.

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3 years ago

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valentina_108 [34]

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3 years ago

Considering that the mantle is 44.8% oxygen and 21.5% silicon by mass, calculate the mole ratio of oxygen atoms to silicon atoms

horrorfan [7]

The mantle has a mass of around $4.278 X 10 ^2^4 kg$ that is around 68.4% of earth's mass.

So to calculate moles we need to first find out the mass of oxygen and silicon present in mantle. It is given that oxygen is 44.8% by mass in mantle and 21.5% by mass in mantle, therefore to calculate its mass, we need to use $\text{mass percentage }=\frac{\text{mole of solute}}{\text{mass of solution}}\times100$

Now, to calculate mass percentage of oxygen

$44.8 =\frac{x}{4.278X10^2^4kg}\times100$

$x= 191.65\times10^2^2kg$

Similarly the mass of silicon can be calculated

$21.5 =\frac{x}{4.278X10^2^4kg}\times100$

$x=91.977\times10^2^2kg$

Now, the moles of any substance is calculated by

$\text{moles}= \frac{\text{given mass}}{\text{molar mass}}$

$\text{moles of oxygen}= \frac{191.65\times10^2^2kg}{2.6566962\times10^-^2^6kg}$

where, mass of oxygen in kilograms is $2.6566962\times10^-^2^6kg$

So, $\text{moles of oxygen}=72.1384\times10^4^8\text{moles of O}$

Similarly $\text{moles of silicon}= \frac{91.977\times10^2^2kg}{4.663\times10^-^2^6kg}$

$\text{moles of silicon}=19.724\times10^4^8\text{moles of Si}$

Now, to calculate mole ratio we need to divide every moles to the lowest calculated mole that is the moles of Si and round it off to the nearest whole number.

$\text{mole ratio of oxygen}= \frac{72.138\times10^4^8kg}{19.724\times10^4^8kg}$