The average atomic mass of element X is 14.007 u.
The average atomic mass of X is the <em>weighted average</em> of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its <em>relative importance</em> (i.e., its % abundance).
Thus,
0.996 36 × 14.003 u =13.952 03 u
0.003 64 × 15.000 u = <u>0.054 60 u</u>
__________TOTAL = 14.007 u
1) is the answer because the only way to turn it from blue to yellow is to mix it with an acidic solution.
Answer : The temperature of this gas will be, 206.9 K
Explanation :
The expression for the kinetic energy per molecule of monoatomic gas (argon) is:
...........(1)
The expression for the kinetic energy per molecule of diatomic gas (nitrogen gas) is:
.............(2)
The total kinetic energy of the molecule will be,

Now put all the expression in this, we get:


Now put all the given values in this expression, we get:


Therefore, the temperature of this gas will be, 206.9 K
b. a chemical that cannot be broken down or separated into other chemicals
Answer:
The contributions are not listed in the question. I guess the following are the options you are talking about.
Same elements have same properties:
In 1803 Dalton gave the atomic theory that the properties of the atoms of the same element are same.
Electrons in Orbits:
Electrons were discovered in 1897 by J J. Thompson but the hypothesis of electrons in the orbits were given by Hantaro Nagaoka in 1904.
Plum pudding model:
Plum pudding model was given by J. J. Thompson in 1904 with the concept of positively charged medium containing the negatively charged electrons in it.
Positively Charged Atomic Nucleus:
Earnest Rutherford in 1911 discovered the positively charged atomic nucleus.