<h3>
Answer:</h3>
42960 years
<h3>
Explanation:</h3>
<u>We are given;</u>
- Remaining mass of C-14 in a bone is 0.3125 g
- Original mass of C-14 on the bone is 80.0 g
- Half life of C-14 is 5370 years
We are required to determine the age of the bone;
- Remaining mass = Original mass × 0.5^n , where n is the number of half lives.
Therefore;
0.3125 g = 80.0 g × 0.5^n
3.90625 × 10^-3 = 0.5^n
- Introducing logarithm on both sides;
log 3.90625 × 10^-3 = n log 0.5
Solving for n
n = log 3.90625 × 10^-3 ÷ log 0.5
= 8
- Therefore, the number of half lives is 8
- But, 1 half life is 5370 years
- Therefore;
Age of the rock = 5370 years × 8
= 42960 years
Thus, the bone is 42960 years old
Answer:
sorry I have no idea what the answer is
Moles of K = 32.4/39 = 0.83 mole. According to stoichiometry, 2 moles of K produces 1mole of H2. Therefore, 0.83 mole of K produces = 0.83/2 = 0.415 moles of H2. Therefore number molecules of H2 = moles of H2 x 6.02 x 10^23 = 2.4983 x 10^23 molecules. Hope this helps!
Answer:
114.7g
Explanation:
Given parameter:
Mass of Na = 45g
Unknown:
Mass of produced NaCl = ?
Solution:
The reaction equation is shown below;
2Na + Cl₂ → 2NaCl
Now, we solve from the known to the unknown. The known here is the mass of Na and it is sufficient to solve the problem;
Number of moles = 
Molar mass of Na = 23g/mol
Number of moles = 
= 1.96moles
2 mole of Na produced 2 moles of NaCl
1.96 moles of Na will produce 1.96 moles of NaCl
Mass of NaCl = number of moles x molar mass
= 1.96 x [23 + 35.5]
= 114.7g
<span>The notation of the isotopes using the atomic number and the mass number consists of the symbol of the atom, preceded by the mass number as a superscript and the atomic number as a superscript.
All the isotopes of the same element have the same atomic number. They only vary the mass number.
So, all the isotopes of oxygen have atomic number 8.
The isotope oxygen-16 has mass number 16, so it is written with the symbol O preceded by the number 16 as a superscript and the number 8 as a subscript (the two numbers to the right of the chemical symbol).
The isotope oxygen-17 has mass number 17, so it is written with the symbol O preceded by the number 17 as a superscript and the number 8 as a subscript.
The isotope oxygen-18 has mass number 18, so it is written with the symbol O preceded by the number 18 as a superscript and the number 8 as a subscript.</span>
