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Jobisdone [24]
3 years ago
11

A 806.3 ng sample of an unknown radioactive substance was placed in storage and its mass measured periodically. after 47 days th

e amount of radioactive substance had decreased to 100.8 ng. how many half-lives of the unknown radioactive substance have occurred?
Chemistry
1 answer:
skelet666 [1.2K]3 years ago
3 0
The substance has completed 3 half lives.
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For the reaction below determine the ▲H for the reaction and state whether the reaction was endothermic or exothermic. Show your
scoundrel [369]

Answer:exothermice

Explanation: it is relaeing heat not keeping  it in

6 0
2 years ago
Name the two criteria that is used to determine if a substance is pure or not​
meriva

Answer:

Melting and Boiling Point Determination

The physical properties of a substance can be used to establish its purity. These properties include the melting point and boiling point. Different substances tend to have different melting and boiling points, and any pure substance will have a specific melting and boiling point.

3 0
3 years ago
Why would we want to correct for water vapor?
rosijanka [135]

Answer:

The vapor pressure due to water in a sample can be corrected for in order to get the true value for the pressure of the gas.

Explanation:

4 0
3 years ago
A block of iron has the dimensions of 3.00 cm × 3.00 cm × 3.00 cm. It has a mass of 213 g. What is it's density?
Novosadov [1.4K]

Answer:

About 7.89g/cm^3, I think.

Explanation:

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6 0
3 years ago
Balance the following chemical equation<br> Na+I2-&gt;NaI
jenyasd209 [6]

Balanced equation : 2Na+I₂⇒2NaI

<h3>Further explanation </h3>

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:

• 1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc.

• 2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product

• 3. Select the coefficient of the substance with the most complex chemical formula equal to 1

Reaction

Na+I₂⇒NaI

  • Give coefficient :

aNa+bI₂⇒NaI

  • Make an equation :

Na, left=a, right=1⇒a=1

I, left=2b, right=1⇒2b=1⇒b=0.5

Equation becomes :

Na+0.5I₂⇒NaI x 2

2Na+I₂⇒2NaI

3 0
3 years ago
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