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3 years ago

1. 1.204 x 1024 atoms He = ? moles He

Chemistry

1 answer:

Fantom [35]3 years ago

5 0

Check your chemistry textbook (or class notes) concerning molar mass, then look up the value for oxygen.

Then divide Avogadro’s number into the given amount of atoms, to find the number of moles.

Then combine this result appropriately with the molar mass, and voilà!

…Then reconsider posting homework questions without showing the work you have already done.

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When a soda can is dropped, it should not be immediately opened. Why?

Kipish [7]

The pressure inside a coke bottle is really high. This helps keep the soda carbonated. That is, the additional pressure at the surface of the liquid inside the bottle forces the bubbles to stay dissolved within the soda. When the coke is opened, there is suddenly a great pressure differential. The initial loud hiss that is heard is this pressure differential equalizing itself. All of the additional pressure found within the bottle pushes gas out of the bottle until the pressure inside the bottle is the same as the pressure outside the bottle. However, once this occurs, the pressure inside the bottle is much lower and the gas bubbles that had previously been dissolved into the soda have nothing holding them in the liquid anymore so they start rising out of the liquid. As they reach the surface, they pop and force small explosions of soda. These explosions are the source of the popping and hissing that continues while the soda is opened to the outside air. Of course, after a while, the soda will become "flat" when the only gas left dissolved in the liquid will be the gas that is held back by the relatively weak atmospheric pressure.

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3 years ago

Some properties of liquid water are very different from those of solid water (ice). Explain why freezing is considered a physica

drek231 [11]

Answer:

A chemical change is a change in the chemical makeup of a substance and results in a new substance. Ice and water both have the same chemical makeup - ice is just a different state and has the same atoms but in an expanded form.

Explanation:

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3 years ago

Which of the following equations has correct formulas and also is a balanced equation?

aliya0001 [1]

Answer : The correct option is, (B)

Explanation :

Balance equation : Balanced equation are those equation in which the number of atoms of each element and the total charge must be same on products side and reactants side.

In the given options, only option (B) equation has correct formula and also a balanced equation.

$2Be+O_2\rightarrow 2BeO$

while the other options has incorrect formulas and also an unbalanced equations.

The correct equation for option A is, $CaCO_3\rightarrow CaO+CO_2$

The correct equation for option C is, $2Mg+O_2\rightarrow 2MgO$

The correct equation for option D is, $KCl+HNO_3\rightarrow HCl+KNO_3$

Hence, the correct answer is, (B) $2Be+O_2\rightarrow 2BeO$

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3 years ago

If 500g of copper melts at 1085°C, at what temperature would 250g of copper melt?

Alex787 [66]

Answer:

the copper would melt at the same temperature no matter how much quantity there is so 1085

Explanation:

6 0

3 years ago

Use MO diagrams to place B2+, B2, and B2- in order of (a) decreasing bond energy; (b) decreasing bond length.

shepuryov [24]

We use the MO diagram for a homonuclear diatomic species (since C and N are neighbours, we treat them as the "same").

The first two electrons contribute to bonding. The next two are anti-bonding.

The next six contribute to bonding, and the following six are anti-bonding.

So, if we start with CN+, which has 4+5-1 (8) valence electrons, we note that the first two electrons contribute to bonding, while the next two cancel this out; the next four contribute to bonding, so the bond order is 4/2 = 2.

If we add one more electron to get CN, there are now 5 bonding electrons, giving bond order 5/2=2.5.

Adding one more to give CN- would give the bond order 6/2 = 3. (If we added more electrons, each one would lower the bond order.)

Given a series of molecules with identical skeletal structures, the one with the highest bond order has the highest bond energy:

CN+ < CN < CN-

Lewis structures will verify that CN- has a triple bond, but they do not work particularly well for CN+ and CN.

learn more about bond orders at

brainly.com/question/9713842

#SPJ1

3 0

2 years ago