Average atomic mass of an element is the sum of atomic mass of its isotopes multiplied by their respective percentage abundance.
There are four isotopes of element X:
1. 4.350 % with mass 49.94605 amu
2. 83.79% with mass 51.94051 amu
3. 9.5% with mass 52.94065 amu
4. 2.360% with mass 53.93888 amu
Thus, average atomic mass will be:

Or,

Therefore, average atomic mass of element X will be 51.99 amu (four significant figures)
Answer:
okay buddy I can't help u that much but use socratic (app)
Explanation:
it will find u the best possible answer...it helped when I was doing my vectors homework
Answer:
density equals weigt divided by volume
Explanation:

The question is incomplete.
The complete question probably is
The pH scale for acidity is defined by pH = − log₁₀[H⁺] where [H⁺] is the concentration of hydrogen ions measured in moles per liter (M). A solution has a pH of 2.55. Find the hydrogen ion concentration.
Answer: -
0.003 M
Explanation: -
pH = − log₁₀[H⁺]
Thus the hydrogen ion concentration [H⁺] = 
= 
= 0.003 M
Answer:
I would say D (not sure tho)
Explanation: