Answer:
63. 55 amu
Explanation:
Copper is known to exist in two different isotopes which are Cu-63 and Cu-65.
Cu-63 has an atomic mass of 62.93 amu and it has an abundance of 69.15%.
Similarly,
Cu-65 has an atomic mass of 64.93 amu and it has an abundance of 30.85%
Therefore, using the weighted average mass method, the atomic mass of copper is:
Atomic mass of copper = (0.6915*62.93) amu + (0.3085*64.93) amu = 43.52 amu + 20.03 amu = 63.55 amu
Thus, the atomic mass of copper (express in two decimal places) is 63.55 amu
Answer:
A. True
Explanation:
The octane number is determined by comparing the characteristics of gasoline to isooctane (2,2,4-trimethylpentane) and heptane. The correct option is option A.
Basically, the higher the octane number, the greater the resistance of the gasoline to knocking.
Answer:
The formula of ammonium fluoride is NH4F.
Explanation:
1 The atoms in each ion are bonded together covalently to form a single unit.
Wrong!
⇒ The atoms in an ion compound are linked together by an ionic bond.
2 The charge is distributed over the entire ion.
Wrong!
Ions have taken in or given up electrons. This happens in the atomic shell.
3 The formula of ammonium fluoride is NH4F.
Right!
4 The formula of potassium sulfate is K2SO
Wrong!
The formula for potassium sulfate is K2SO4.
The answer is C to achieve an octet of valence electrons so they become stable