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geniusboy [140]
2 years ago
8

A radioactive substance has a half-life of 5 million years. What is the age of a rock in which 25% of the original radioactive a

toms remain? You must show your work or explain how you came up with your answer for full credit.
Chemistry
1 answer:
GenaCL600 [577]2 years ago
5 0

Answer:

10 million years

Explanation:

For a sample to decay to 25% of its original amount, 2 half lives must have passed. Since one half life is 5 million years, multiplying this by 2 gives us that 2 half lives is 10 million years.

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Which of the following elements has the largest electronegativity? A) Bismuth B) Nitrogen C) Potassium D) Arsenic​
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The melting points of alkaline earth metals are many times higher than those of the alkali metals. Explain this difference on th
7nadin3 [17]

The correct answer is higher melting point, bound by metal metal bonds.

While alkali metals only have one valence electron, alkaline earth metals have two. Metal to metal connections hold the metals together. Alkaline earth metals have a stronger metallic connection and a higher melting point because they have two valence electrons.

the characteristics that Group 2 metals excel in over Group 1 metals.

  • Initial Ionization Potential
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  • Strong propensity to produce bivalent compounds

As a result, group 2 metals have stronger metallic bonding, which leads to increased cohesive energy and compact atom packing. This explains why group 2 metals are harder and have higher melting and boiling temperatures than group 1 metals.

To learn more about  Group 2A(2) refer the link:

brainly.com/question/9431096

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3 0
2 years ago
Which two chemical substances are needed to begin the photosynthesis factory process?
Rudiy27
<span>Carbon dioxide CO2 and water H2O. Through photosynthesis makes sugar C6H12O6.</span>
5 0
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7. NH2CO2NH4(s) when heated to 450 K undergoes the following reaction to produce a system which reaches equilibrium: NH2CO2NH4(s
Taya2010 [7]

Answer:

Value of equilibrium constant is 0.0888

Explanation:

Both NH_{3} and CO_{2} are gaseous. Hence equilibrium constant depends upon partial pressures of NH_{3} and CO_{2}.

Initially no NH_{3} and CO_{2} were present.

Hence mole fraction of NH_{3} and CO_{2} at equilibrium can be calculated from coefficient of NH_{3} and CO_{2} in balanced equation.

Mole fraction of NH_{3} = (number of moles of NH_{3})/(total number of moles of NH_{3} and CO_{2}) = \frac{2moles}{(2+1)moles}=\frac{2}{3}

Mole fraction of CO_{2} = (number of moles of CO_{2})/(total number of moles of NH_{3} and CO_{2}) = \frac{1moles}{(2+1)moles}=\frac{1}{3}

Let's assume both CO_{2} and NH_{3} behaves ideally.

Therefore partial pressure of NH_{3}, P_{NH_{3}}= x_{NH_{3}}.P_{total} and P_{CO_{2}}= x_{CO_{2}}.P_{total}

Where x represents mole fraction

So, P_{NH_{3}}=\frac{2}{3}\times 0.843atm=0.562atm

P_{CO_{2}}=\frac{1}{3}\times 0.843atm=0.281atm

So, K_{p}=P_{NH_{3}}^{2}.P_{CO_{2}}=(0.562)^{2}\times 0.281=0.0888

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3 years ago
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