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DENIUS [597]
3 years ago
13

Help please if its right i'll give brainiest

Chemistry
1 answer:
Mkey [24]3 years ago
5 0
I believe it is spontaneous generation
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If the temperature is 80° outside does the air transfer more or less thermal energy to a thermometer then if it is 60°
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Less, because thermal energy is heat so if it gets colder there is less thermal energy.
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3 years ago
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Promethium-147 is sometimes used in luminescent paint. It has a half-life of 956.3 days. If 250 grams (g) of promethium-147 is u
Fantom [35]

Answer:

% = 76.75%

Explanation:

To solve this problem, we just need to use the expressions of half life and it's relation with the concentration or mass of a compound. That expression is the following:

A = A₀ e^(-kt)   (1)

Where:

A and A₀: concentrations or mass of the compounds, (final and initial)

k: constant decay of the compound

t: given time

Now to get the value of k, we should use the following expression:

k = ln2 / t₁/₂   (2)

You should note that this expression is valid when the reaction is of order 1 or first order. In this kind of exercises, we can assume it's a first order because we are not using the isotope for a reaction.

Now, let's calculate k:

k = ln2 / 956.3

k = 7.25x10⁻⁴ d⁻¹

With this value, we just replace it in (1) to get the final mass of the isotope. The given time is 1 year or 365 days so:

A = 250 e^(-7.25x10⁻⁴ * 365)

A = 250 e^(-0.7675)

A = 191.87 g

However, the question is the percentage left after 1 year so:

% = (191.87 / 250) * 100

<h2>% = 76.75%</h2><h2>And this is the % of isotope after 1 year</h2>
3 0
3 years ago
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What is the mass of hydrogen in 5.5 mol of Ca(OH)2?​
Morgarella [4.7K]

Answer:

12*2*6.022*10^23. Atoms of hydrogen.

Explanation:

First of all if u know that 1 molecule of calcium hydroxide contain 2 hydrogen atom and 1 mole of calcium hydroxide contain 6.022*10^23 molecules of calcium hydroxide.

Hence 1 mole of calcium hydroxide contain 2*6.022*10^23 atom of hydrogen.

So 12 mole of calcium hydroxide contain =12*2*6.022*10^23. Atoms of hydrogen.

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Which climate is it marking brainliest
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Answer:

D highland

Explanation:

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What is the percent composition of water found in tin (IV) oxide octahydrate?
Tomtit [17]

Answer:

tin (IV) oxide octahydrate contains 8 part water

What is the percent composition of water found in tin (IV) oxide octahydrate?

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