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Phoenix [80]
3 years ago
9

How many moles does 205g of helium, He contains ?

Chemistry
2 answers:
Ne4ueva [31]3 years ago
7 0
<span>Moles = weight in g / atomic weight So, moles in 40 g of He = 40 / 4 = 10 moles.</span>
Travka [436]3 years ago
7 0
19.512 
i hope this helps

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Your bedroom gets direct sunlight through a window during the hottest times of the day. you ask your mom to turn down the thermo
Kipish [7]

If you take your mom's advice, a. the room will be cooled by minimizing heat transfer by reflection.

The Sun is heating your room by its <em>radiation</em>.

The aluminium foil is shiny, so it reflects the Sun’s radiation back outside the window.

<em>Convection</em> is the transfer of heat caused by the air moving around in your room.

<em>Conduction</em> occurs only when a hot object is in contact with a cooler object.

5 0
3 years ago
A student estimated the volume of a liquid in a beaker as 200.0 mL. When she poured the liquid into a graduated cylinder she MEA
Taya2010 [7]

Answer:

<h3>The answer is 0.91 %</h3>

Explanation:

The percentage error of a certain measurement can be found by using the formula

P(\%) =  \frac{error}{actual \:  \: number}  \times 100\% \\

From the question

actual volume = 198.2 mL

error = 200 - 198.2 = 1.8

So we have

P(\%) =  \frac{1.8}{198.2}  \times 100 \\  = 0.90817356205...

We have the final answer as

<h3>0.91 %</h3>

Hope this helps you

6 0
3 years ago
Is atomic weight a whole number or not a whole number
steposvetlana [31]

Answer:

Atomic mass of an element is not a whole number because It contains isotopes. For example, chlorine has two isotopes 1735Cl and 1737Cl with natural abundances in the approximate ratio of 3:1. Hence, the average atomic mass of chlorine is approximately 35.5 g/mol.

Hope this helps! If so please mark brainliest and rate/heart if it did to help my account out!!

3 0
3 years ago
How to know how many valence electrons are in an element
Alenkinab [10]

Answer:

Hope it helped

Explanation:

For neutral atoms, the number of valence electrons is equal to the atom's main group number. The main group number for an element can be found from its column on the periodic table. For example, carbon is in group 4 and has 4 valence electrons. Oxygen is in group 6 and has 6 valence electrons.

7 0
3 years ago
Which of the following would you except to see in the death of a star that is less than 0.5 solar mass
Ket [755]

B. White Dwarf.

<h3>Explanation</h3>

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As the outer layers of gas leave the core and cool down, they become no longer visible. The only thing left is the core of the star. Consider the Chandrasekhar Limit:

Chandrasekhar Limit: 1.4 \;M_\odot.

A star with core mass smaller than the Chandrasekhar Limit will not overcome electron degeneracy and end up as a white dwarf. Most of the outer layer of the star in question here will be blown away already. The core mass of this star will be only a fraction of its 0.5 \;M_\odot, which is much smaller than the Chandrasekhar Limit.

As the star completes the triple alpha process, its core continues to get smaller. Eventually, atoms will get so close that electrons from two nearby atoms will almost run into each other. By Pauli Exclusion Principle, that's not going to happen. Electron degeneracy will exert a strong outward force on the core. It would balance the inward gravitational pull and prevent the star from collapsing any further. The star will not go any smaller. Still, it will gain in temperature and glow on the blue end of the spectrum. It will end up as a white dwarf.

7 0
3 years ago
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