The half-life of Th-232 is 1.405 × 10¹⁰ years
Time elapsed = 2.8 x 10⁹ years
Equation of radioactive decay:
A = A₀ = (1/2)^ t/t₁/₂
where A₀ is the initial amount, A is the amount after time t, t₁/₂ is the half file
The fraction of thorium-232 that remains in the rock after 2.8 billions years is,
A/A₀ = (1/2) ^ (2.8 x 10⁹/ 1.405 × 10¹⁰) = 0.871
Therefore, the percentage of thorium-232 in the rock that was dated at 2.8 billions year = 87.1%
Okay your answer is 1 I think
Answer is A . He shot tiny alpha particles thought a piece of gold foil
Answer:
D. chlorine, oxygen, nitrogen, hydrogen.
Explanation:
- Thomas Graham found that, at a constant temperature and pressure the rates of effusion of various gases are inversely proportional to the square root of their masses.
<em>ν ∝ 1/√M</em>
where ν is the rate of effusion and M is the atomic or molecular mass of the gas particles.
- The molecular mass for the listed gases are:
O₂: 32.0 g/mol,
Cl₂: 70.906 g/mol,
N₂: 28.0 g/mol,
H₂: 2.0 g/mol.
- Hence, the smallest molecular mass of the gas, the fastest rate of effusion.
So, the order from the slowest to the fastest rate of effusion is:
<em>Chlorine, oxygen, nitrogen, hydrogen.</em>
If you have a book, read it!! I promise you, it tells you this answer!
