Element X is found in two forms: 90.0% is an isotope that has a mass of 20.0, and 10.0% is an isotope that has a mass of 22.0. What is the atomic mass of element X?
A. 20.0
B. 20.2
C. 20.8
D. 21.2
E. 21.8
Can anyone explain this one for me?
Solution 1
answer: B
Solution 2
The relative atomic mass of element X which has 2 isotopes is 20.2 u.
What is relative atomic mass ?
Relative atomic mass of an element is an average of masses of atoms of isotopes. It is found out by the formula ,
relative atomic mass=(mass×abundance of isotope 1 )+(mass×abundance of isotope 2)/100
Considering the example given ,atomic mass of element X is found out as,
relative atomic mass=(20×90)+(10×22)/100=2020/100=20.2 u.
Relative atomic mass is a dimensionless physical quantity which is an average ratio of mass of atoms in a sample to the atomic mass constant.Atomic mass constant is 1/12 of mass of carbon-12 atom.
Average atomic mass is relative atomic mass which is calculated from percent composition.Relative atomic mass is unit less and is a physical quantity.It is a multiple of standard atomic mass unit.
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A. It is moving toward Earth.
B. It is moving very fast.
C. It is slowing down.
D. It is moving away from Earth.
Therefore the answer is D.
Hoped I helped:D
a. A pH of 10 is two times as basic
b. A pH of 8 is two times as basic
c. A pH of 10 is 2,000 times as basic
d. A pH of 8 is 20 times as basic
e. A pH of 10 is 100 times as basic
A. acceleration
B. mass
C. force
D. weight
Kg.m
F= -------------
S²
The combination of units written kg· [tex]m/s^{2}[/tex]can be used for force.
What is force?
A force is just a factor that can impact an object's motion. A force may cause a mass item to accelerate by changing its velocity. A push as well as a pull can also be used to describe forces. A force is a vector quantity even though it has both magnitude , direction as well. It can be denoted by the symbol F.
The formula of force (F) = m×a.
where, m is mass of the particle and a is acceleration. It is known that unit of mass is kg and acceleration is [tex]m/s^{2}[/tex].
Now, put the unit of given data in above formula.
F= kg×[tex]m/s^{2}[/tex].
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in chemistry
Change in speed = (25 - 15) = 10 m/s
Time = 15 s
Acceleration = 10/15 = 2/3 m/s
A. sunspot maxima and minima
B. condensation of a nebula
C. formation of a crater
D. formation of a black hole
has been found to vary up and down in a cycle of very very roughly
about 11 years.
It's importaint to first set up the equation. 2AgNO3+Cu--->Cu(NO3)2+2Ag this will dtermine whether you need to divide by two when you divide the moler mass of silver nitrate with 4g to find the amout of moles.023547419, then you divide by two and multiply by the molor mass of CU(NO3)2 and you should get your answer. I got 2.208grams. (please tell me if i'm wrong, going to be an AP Chemistry student.), i copyed myself so don't ban me.
Answer:
0.7479 grams of copper is required to replace 4.00 grams of silver nitrate.
Explanation:
[tex]Cu+2AgNO_3\rightarrow Cu(NO_3)_2+2Ag[/tex]
Moles of silver nitrate = [tex]\frac{4.00 g}{169.87 g/mol}=0.0235 mol[/tex]
According to reaction 2 moles of silver nitrate reacts with 1 mole of copper metal.
Then 0.02354 moles of silver nitrate will react with:
[tex]\frac{1}{2}\times 0.0235 mol=0.01177 mol[/tex]
Mass of 0.01177 moles copper =0.01177 mol × 63.55 g/mol = 0.7479 g
0.7479 grams of copper is required to replace 4.00 grams of silver nitrate.
so, a= 91.28 N / 9.6 kg = 9.5 m/s^2.(final answer)
1. positive and negative charges repel
2. two positive charges attract
3. two negative charges attract
4. positive and negative charges attract
4, why you need to post this it's too dang easy, I thought this was going to be chanlanging. remember eletrons go around a nucleus for a reason.