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dalvyx [7]
3 years ago
13

When finding the mass number of an element do you round the atomic mass up or down? Ex. atomic mass of 74.9216, is the mass numb

er 75 or 74
Chemistry
2 answers:
Margaret [11]3 years ago
5 0
The total number of protons and neutrons in an atom is called the mass number. You can find the mass numberfor any element. The mass number canbe found by rounding the average atomic mass to the nearest whole number.
as an example
6.25 is closer to 6 than 7 so it is 6
6. 50 is closer to 7 so it is 7
you have to look at the thenth digit. if the number is 4 or less you have to round it down
if the tenth digit is 5 or greather than you have to round it up.
AleksAgata [21]3 years ago
3 0
Round the answer to the nearest whole number.
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Name the following alkyne.<br> Please help me &lt;3
Alexandra [31]

Answer:

D. 7-methyl-3-octyne

Explanation:

1) Identify the parent chain and name it like an alkane.

• The longest chain of carbons, which consists of the functional group (which is the alkyne group in this case: C≡C).

• There are 8 carbons in the longest chain, so it is called an octane.

2) Now, identify the location of the functional group.

• The location number of the functional group should be as low as possible. Thus although we could count from the right, we start counting from the left since the functional group is closer to the left. From the left, the functional group would be at carbon 8 while from the left, it is on carbon 3.

• Replace 'ane' with 'yne' in octane for the alkyne group.

• This would give us 3-octyne.

3) Lastly, add in the name of the branch.

• Here we have one branch, -CH₃. This is read as methyl.

• Identify the location number of the branch by counting the number of carbons in the same direction as when we counted the location number of the functional group. The methyl branch has a location number of 7.

• Adding the name of the branch before the parent chain, we would arrive at 7-methyl-3-octyne as the IUPAC name of the alkyne.

Further Explanation:

A) This option is incorrect as there are only 8 carbons in the parent chain. Although there are 9 carbons in total, the 9th carbon is taken care of in '7-methyl'.

B) Location number of the functional group should be as low as possible, so start counting the number of carbons from the left!

C) Since the functional group is an alkyne, the word 'octane' should be 'octyne' instead.

8 0
3 years ago
Which term best describes how the solar system form?
KengaRu [80]
Which figure is closest to the age of the solar system?
4.5 billion years

What force pulled the solar system together out of a cloud of gas and dust?
Gravity

Which term best describes how the solar system is formed?
Gradually
5 0
3 years ago
Read 2 more answers
I need chemistry help! How would I set up these problems?
Bond [772]

Answer: -

1) 8.33 minutes

2) 118.39 in/ s

180.43 m/min

10.83 km/ hr

Explanation: -

Speed of light = 3 x 10⁸ m/s

Distance of the earth from the sun= 93 million miles

We know 1 million = 1,000,000

Also 1 mile = 1609 m

Distance of the earth from the sun= 93 million miles

= 93,000,000 miles.

= 1.5 x 10^{11} m

Time taken = \frac{Distance}{Speed}

= \frac{1.5 x [tex] 10^{11} m}{3 x 10⁸ m/s} [/tex]

= 500 s

= 500/ 60

= 8.33 minutes

2) Distance = 1 mile = 63360 inches

Time taken = 8.92 min

= 8.92 x 60

= 535.2 s

Speed = \frac{distance}{time}

= \frac{63360 inches}{535.2 s}

= 118.39 in/ s

Distance = 1 mile = 63360 inches = 63360 x 2.54 cm = 63360 x 2.54 x 10^{-2} m

Time taken = 8.92 min

Speed = \frac{distance}{time}

= \frac{63360 x 2.54 x [tex] 10^{-2} m}{8.92 min} [/tex]

= 180.43 m/ min

1 m = 10⁻³ Km

1 min = 1/60 hour

1 m /min = 10⁻³ km/ \frac{1}{60 hour}

= 60/1000

=0.06 km/hr

180.43 m / min = 180 x 0.06 km / hr

= 10.93 km / hr

4 0
3 years ago
Charles’s law states that at a constant pressure, Th e volume of a given amount of gas is ____ to its absolute temperature
lawyer [7]

Answer:

Directly proportional.

Explanation:

Directly proportional to it's absolute temperature.

7 0
4 years ago
What is the surprising thing that happens in a superconductor?
r-ruslan [8.4K]
With almost all substances . . .

-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.

-- If you keep making them colder, their resistance keeps decreasing,
but it never completely disappears, no matter how cold you make them.


But with a few surprising substances, called 'superconductors' . . .

-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.

-- If you keep making them colder, then suddenly, at some magic 
temperature, their resistance COMPLETELY disappears.  It doesn't 
just become small, and it doesn't just become too small to measure.  
It becomes literally totally and absolutely ZERO.  

If you start a current flowing in a superconducting wire, for example, 
you can connect  the ends of the wire together, and the current keeps 
flowing around and around in it, for months or years.  As long as you 
keep the loop cold enough, the current never decreases, because
the superconducting wire has totally ZERO resistance.

Did somebody say "What's this good for ?  What can you do with it ?"

1).  Every CT-scan machine and every MRI machine needs many 
powerful magnets to do its thing.  They are all electromagnets, with 
coils of superconducting wire, enclosed in containers full of liquid helium.  
Yes, it's complicated and expensive.  But it turns out to be simpler and 
cheaper than using regular electromagnets, with coils of regular plain
old copper wire, AND the big power supplies that would be needed
to keep them going.

2).  Resistance in wire means that when current flows through it,
energy is lost.  The long cables from the power-generating station
to your house have resistance, so energy is lost on the way from the
generating station to your house.  That lost energy is energy that the
electric company can't sell, because they can't deliver it to customers.

There are plans to build superconducting cables to carry electric power
from the producers to the customers.  The cables will be hollow pipes,
with liquid helium or liquid hydrogen inside to keep them cold, and 
something on the outside to insulate them from the warmth outside.
Yes, they'll be complicated and expensive.  But they'll have ZERO
resistance, so NO energy will be lost on its way from the generating 
stations to the customers.  The power companies think they can
build superconducting 'transmission lines' that will cost less than
the energy that's being lost now, with regular cables.
8 0
4 years ago
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