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Furkat [3]
3 years ago
9

What would the percentage of thorium-232 (parent compound) be in a rock that was dated at 2.8 billions years?

Chemistry
1 answer:
just olya [345]3 years ago
5 0

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%


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A glass flask has a volume of 500 mL at a temperature of 20° C. The flask contains 492 mL of mercury at an equilibrium temperatu
OverLord2011 [107]

Answer:

101.63° C

Explanation:

Volume expansivity γa = γr -  γ g = 18 × 10⁻⁵ - 2.0 × 10⁻⁵ = 16 × 10⁻⁵ /K

v₂ - v₁ / v₁θ = 16 × 10⁻⁵ /K

(500 - 492 ) mL / (492 × 16 × 10⁻⁵) = θ

θ = 101.63° C

4 0
3 years ago
The density of water is 1 gm/ml. An object has a mass of 58 grams. What volume must it have in order to float in water?
Keith_Richards [23]

Answer:

58mL

Explanation:

Given parameters:

Density of water  = 1g/mL

Mass of object  = 58g

Unknown:

The volume the object must have to be able to float in water = ?

Solution:

To solve this problem, we know that the object must have density value equal to that of water or less than that of water to be able to float.

We then set its density to that of water;  

   Density  = \frac{mass}{volume}  

      Volume  = \frac{mass}{density}  

So;

      Volume  = \frac{58}{1}   = 58mL

7 0
2 years ago
I suck at this stuff. HELP
erastovalidia [21]
What do you need help with
7 0
3 years ago
You decide you want to carry a boulder home from the beach. It is 20 centimeters on each
e-lub [12.9K]

Answer:

Weight of boulder = 22,400 gram

Explanation:

Given:

Volume = 8,000 cm³

Density = 2.8

Find:

Weight of boulder

Computation:

Weight of boulder = Volume x Density

Weight of boulder = 8,000 x 2.8

Weight of boulder = 22,400 gram

3 0
3 years ago
In one of his experiments, Lavoisier placed 10.0 grams of mercury (II) oxide into a sealed container and heated it. The mercury
inysia [295]

Oxygen gas produced : 0.7 g

<h3>Further explanation</h3>

Given

10.0 grams HgO

9.3 grams Hg

Required

Oxygen gas produced

Solution

Reaction⇒Decomposition

2HgO(s)⇒2Hg(l)+O₂(g)

Conservation of mass applies to a closed system, where the masses before and after the reaction are the same

mass of reactants = mass of products

mass  HgO = mass Hg + mass O₂

10 g = 9.3 g + mass O₂

mass O₂ = 0.7 g

4 0
3 years ago
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