1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
butalik [34]
3 years ago
6

The element lanthanum has two stable isotopes, lanthanum-138 with an atomic mass of 137.9 AMU and lanthanum-139 with an atomic m

ass of 138.9 AMU.
From the atomic weight of La = 138.9, one can conclude that:

A. there is an isotope of lanthanum with an atomic mass of 138.9
B. lanthanum-139 has the highest percent natural abundance
C. lanthanum-138 has the highest percent natural abundance
D. both isotopes have the same percent natural abundance
Chemistry
1 answer:
dmitriy555 [2]3 years ago
7 0

Answer:

A. there is an isotope of lanthanum with an atomic mass of 138.9

Explanation:

By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.

Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.

Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.

Thus, the correct option is:

<u>A. there is an isotope of lanthanum with an atomic mass of 138.9.</u>

You might be interested in
What is the molarity of a 0.250 L MgCl2 solution that contains 0.175 mol MgCl2?
spayn [35]

Explanation:

we know that 0.250 L = 0.250 dm3

molarity = concentration in dm3/ volume

molarity = 0.175/0.250 = 0.7 mol/dm3

4 0
2 years ago
What is the difference between applied and pure chemistry?
My name is Ann [436]
I hope this helps.
have a great day.

5 0
2 years ago
When two moles of ethane react completely with oxygen, how many moles of carbon dioxide will be produced?A. 2.B. 4.C. 8.D. Unkno
babymother [125]

Answer:

Option B.

Explanation:

As any reaction of combustion, the O₂ is a reactant and the products are CO₂ and H₂O. Combustion reaction for ethane is:

2C₂H₆  +  7O₂   →   4CO₂  +  6H₂O

So 2 moles of ethane react with 7 moles of oxygen to make 4 moles of dioxide and 6 moles of water.

Then 2 moles of ethane will produce 4 moles of CO₂

6 0
2 years ago
Draw all resonance structures for the nitryl fluoride molecule, no2f.
denis-greek [22]
From  electronic  configuration valence electron of  Nitrogen is 5,  oxygen  6x2  which 12 since it  involve  two  molecules ,  that of is frulorine is  7, and  that No2F is 24  which  is  gotten  form  adding (5,12,7  ).All  resonance structure  are  as  follows
       F
 ..    I    ..
: O : N :O: 
 
              ..
     OR  : F:
              I                             

             N                                                  ..                                                                                                                                    : F:

          /         \                        or                   I

   ..                 ..                                               N

:O  :            :O:                                       / /        \\
                                                            / /               \\
                                                         :O :            :  O:
7 0
3 years ago
Pretty sure its easy but i cant-
enyata [817]

Answer:

Tryptophan is an essential amino acid.

5 0
3 years ago
Read 2 more answers
Other questions:
  • Identify the products that are in equilibrium with NH3 and H2O.Identify the products that are in equilibrium with and .NH2−and H
    12·2 answers
  • What are the products of the following reaction C6H6+O2
    6·1 answer
  • For practice, the molecular formula for ascorbic acid is C6H8O6, and you used 6 g in this experiment, calculate the molarity of
    6·2 answers
  • An atom of 118Xe contains___ neutrons?<br>A) 118 B) 54 C) 64 D) 172 E) 110​
    8·1 answer
  • A woman weighing 600 N is leaning on the ground with shoe soles with a total area of ​​0.04 m2. Calculate the pressure of the mo
    14·1 answer
  • For the following following balance the equation and indicate the correct coefficients used. when Methanol (CH3OH) burns in oxyg
    15·1 answer
  • A bicycle is traveling at 14 miles per hour. How many feet will it cover in 55 seconds? Round your answer to the nearest tenth o
    7·1 answer
  • Which definition bests describes an hydrogen bond? 
    15·1 answer
  • Plz, Help! Read the instructions and answer the question! First one to answer will get brainliest!
    7·2 answers
  • Metal objects, such as knifes or bullets, that come into contact with bones can leave trace evidence on them.
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!