It is like an idea that they come up with in an experimeant
This assumption is not valid because, there are some elements which exist in two or more forms; they have the same atomic number but differ in their mass number, which meas that they possess different number of neutrons. These type of element are called isotopes. Isotope have the same atomic number and similar physical and chemical properties but they have different number of neutrons and therefore possess different masses.
Answer:
Down Syndrome- is when you have an extra 21st chromosome.
Turner Syndrome- is when one of the x chromosome is missing or partly there.
Explanation:
There are many more and you can find a complete list online.
Let us suppose that we have 1 mol of FeCr2O4. I'm going to use approximate masses because I have no idea what your periodic table will say. Just put in the exact masses from your periodic table.
Fe = 56
Cr*2 = 2*52 = 104
O4 = 4*16 = 64
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Total = 56 + 104 + 64 = 224
The % oxygen = (64 / 224) * 100 = 28.5 % but none of your answers match this. Perhaps you are talking about Fe2(Cr2O4)3 The brackets make all the difference in the world.
Without going through all the detail I did before, The molecular mass is
Fe * 2 = 112
Cr * 6 = 312
O * 12 = 192
The total molecular mass = 616
The % Oxygen = (192 / 616) * 100 = 31% roughly. That answer isn't there either.
Let's wait and see who else answers.