The rows are called Periods.
B. 1 mole of beryllium, 2 moles of oxygen, 2 moles of hydrogen
Answer:
A.
Explanation:
The <u>tertiary structure </u>of proteins is related to the interactions between the amino acids of the <u>primary structure</u>. Thus, these interactions give it a specific three-dimensional configuration which is very sensitive to <u>functionality</u>.
For example, <u>allosteric inhibitions</u> are related to this concept. When the <u>inhibitor</u> changes the tertiary structure of the protein it loses all <u>activity</u> and for the catalysis of the reaction.
Thus, the primary structure (which is related to the specific <u>sequence of amino acids</u>) will determine the tertiary structure since the chain folds will be a consequence of<u> intra-amino acid interactions</u>.
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>
The given compound is Aluminum sulfate, Al2(SO4)3:
Molar masses:
Aluminum = 27 g/mol
Sulfur = 32 g/mol
Oxygen = 16 g/mol
The total molar mass is 342 g/mol
The ratio by mass of the elements:
Aluminum = 27*2/342
= 0.16
Sulfur = (32*3)/342
= 0.28
Oxygen = (16*12)/342
= 0.56
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