Jacob's teacher shows his class a shaker filled with table salt. Jacob thinks that the salt in the shaker looks like a s

A fossil you are radiometrically dating contains 4 micrograms of Uranium 235 and 4 micrograms of Lead 207. Uranium 235 decays to

Rzqust [24]

The rate at which radioactive substances disintegrate is a constant for a

given radioactive material.

The fossil is 710 million years old.

Reasons:

The half-life of a radioactive material is the time it takes half of the nucleus

of a radioactive material to disintegrate into other forms of materials

through the given off of energy and particles.

The half life of Uranium 235 = 710 million years

The product of the decay of Uranium 235 = Lead 207

The mass of Uranium 235 in the fossil = 4 micrograms

The mass of Lead 207 in the sample = 4 micrograms

Therefore, the mass of Lead 207 in the fossil is equal to the mass of

Uranium 235, therefore, a minimum of half of the Uranium 235 has

decomposed, which gives;

The time of decomposition of the Uranium 235 = 1 Half life = 710 million years

The age of the fossil = The time in which the Uranium has been

decomposing = The time of decomposition = 1 half life of Uranium 235 = 710

million years

The age of the fossil = 710 million years

Using the formula for half-life, we get;

$\displaystyle N(t) = N_0 \left (\dfrac{1}{2} \right )^{\dfrac{t}{t_{1/2}}$

The fossil contains initially only Uranium 235 with a minimum mass of 4 mg

+ 4 mg = 8 mg, which gives;

N₀ = 8 mg

N(t) = The current mass of Uranium 235 = 4 mg

$\displaystyle t_{1/2}$ = 710 million years

$\displaystyle 4 = 8 \cdot \left (\dfrac{1}{2} \right )^{\dfrac{t}{710}$

$\displaystyle \frac{4}{8} = \frac{1}{2} = \left (\dfrac{1}{2} \right )^{\dfrac{t}{710}$

Therefore;

$\displaystyle \left( \frac{1}{2}\right)^1 = \left (\dfrac{1}{2} \right )^{\dfrac{t}{710}$

$\displaystyle 1 = {\dfrac{t}{710}$

t = 710

The age of the fossil, t = 710 million years

Learn more here:

brainly.com/question/20629992

3 0

2 years ago

6. There are three isotopes of silicon. They have mass numbers of 28, 29 and 30. The average atomic mass of silicon is 28.086amu

Elza [17]

Answer:

That means that the isotope that has a mass number of 28 is probably the most abundant. This is because your average atomic mass is 28.086 amu, which is closest to 28.

Formula used to calculate average atomic mass follows:

average atomic mass=(atomic mass of an isotope)*(fractional abundance)

we are given=

Three isotopes of Silicon, which are Si-28, Si-29 and Si-30.

Average atomic mass of silicon = 28.086 amu

As, the average atomic mass of silicon is closer to the mass of Si-28 isotope. This means that the relative abundance of this isotope is the highest as compared to the other two isotopes.

Percentage abundance of Si-28 isotope = 92.2%

Percentage abundance of Si-29 isotope = 4.7 %

Percentage abundance of Si-30 isotope = 3.1%

Hence, the abundance of Si-28 isotope is the highest as compared to the other isotopes.

7 0

3 years ago

What is the volume of 0.128 mol of nitrogen dioxide gas at STP?

Natali5045456 [20]

Answer:

B) 2.87 L

Explanation:

A mole of any gas at STP has a volume of about 22.412 liters. So, 0.128 moles of gas will have a volume of ...

0.128 · 22.412 L ≈ 2.87 L

7 0

3 years ago

Read 2 more answers

What is the final volume, in milliliters, when 5.80 mL of 25.0 %(m/v) NaOH solution is diluted to give a 3.50 %(m/v) NaOH soluti

Zigmanuir [339]

Answer:

41.43 mL

Explanation:

First we calculate the mass of NaOH in the original solution:

25.0 % m/v means that in 100 mL of solution, there are 25 grams of NaOH.

This means that in 5.80 mL, we would have (5.80 * 25/100) 1.45 grams of NaOH.

Then we calculate the volume of the diluted solution, using the grams of NaOH (that remain the same throughout the dilution process):

1.45 g NaOH * $\frac{100 mL}{3.50gNaOH}$ = 41.43 mL

7 0

4 years ago

Please help really soon (I'm confused) :|

Yanka [14]

Answer: carbon dioxide was replaced with oxygen

Explanation:Comparison of Earth's prebiotic and modern atmospheres. Before life began on the planet, Earth's atmosphere was largely made up of nitrogen and carbon dioxide gases. After photosynthesizing organisms multiplied on Earth's surface and in the oceans, much of the carbon dioxide was replaced with oxygen

4 0

3 years ago

Read 2 more answers