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
Thus, the percentage of thorium-232 in the rock that was dated at 2.8 billions year = 87.1%
I don't know this article, but I do know some major changes: first, the change from the plum pudding model (no nucleus, just electrons) to the gold foil experiment, which had Rutherford shoot alpha particles at a sheet of gold only to find them rebounding, proving the existence of a positively charged mass, i.e a nucleus, in the atom. However, this changed again when Bohr realized that the negatively charged electrons should be attracted to the positively charged center, so that there must be something else inside the nucleus.
So 6.02*10^22 is avogadro constant, which is the amount of atoms in one mole. If you look Xenon up in the periodic table you will find it's mass given <span>131,293, which is grams per 1 mole.
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When 6.85×10⁵ cal is converted to kilojoules, the result obtained is 2866.04 KJ
<h3>Data obtained from the question </h3>
- Energy (cal) = 6.85×10⁵ cal
- Energy (KJ) =?
<h3>Conversion scale </h3>
1 cal = 0.004184 KJ
<h3>How to convert 6.85×10⁵ cal to kilojoules</h3>
1 cal = 0.004184 KJ
Therefore,
6.85×10⁵ cal = 6.85×10⁵ × 0.004184
6.85×10⁵ cal = 2866.04 KJ
Thus, 6.85×10⁵ cal is equivalent to 2866.04 KJ
Learn more about conversion:
brainly.com/question/2139943
Answer: 190 g of magnesium chloride can be produced by reacting 2 moles of chlorine gas with excess magnesium bromide.
Explanation:
The balanced chemical reaction is;
is the limiting reagent as it limits the formation of product and 
is the excess reagent.
According to stoichiometry :
1 mole of produces = 1 mole of 
Thus 2 moles of will produce=
of
Mass of 
Thus 190 g of magnesium chloride can be produced by reacting 2 moles of chlorine gas with excess magnesium bromide
