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vladimir2022 [97]
3 years ago
10

You have a radioactive isotope with a mass of 400 grams. The sample has a half life of 5 days. How much is left after 25 days ha

ve passed?
Chemistry
1 answer:
Alexeev081 [22]3 years ago
4 0

Answer:

Amount left after 25 days = 12.5 g

Explanation:

Given data:

Mass of sample = 400 g

Half life of sample = 5 days

Mass left after 25 days = ?

Solution:

First of all we will calculate the number of half lives passes in given time period.

Number of half lives = Time elapsed / Half life

Number of half lives = 25 days/ 5 days

Number of half lives = 5

At time zero = 400 g

At 1st half life = 400 g/2 = 200 g

At 2nd half life = 200 g/2 = 100 g

At 3rd half life = 100 g/2 = 50 g

At 4th half life = 50 g/2 = 25 g

At 5th half life = 25 g/2 = 12.5 g

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Answer:

A chemical equation is balanced when the number of each kind of atom is the same on both sides of the reaction.

Explanation:

    The law of conservation of matter (except in nuclear reactions) indicates that atoms can neither be created or destroyed.

    The number of atoms that are in the  reactants must be the same as the number of the atoms that are in the product.

    The number and types of molecules can (and will) change. The atoms that make up the molecules are rearranged but the number and kinds of atoms stay the same.  

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The sum of protons and neutrons in an atom is called the.
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Atomic mass / mass number / atomic weight

(all of which mean the same thing)
6 0
2 years ago
Which of the following are advantages of the SI system?
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The correct answer is A, B and C
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Which of the following equations of CH4 + Cl2
mylen [45]

Balanced equation : C. CH₄ + 4Cl₂⇒  CCl₄+ 4HCl

<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

CH₄ + Cl₂⇒  CCl₄+ HCl

  • Give coefficient :

aCH₄ + bCl₂⇒  CCl₄+ cHCl

  • Make equation :

C, left=a, right=1⇒a=1

H, left=4a, right=c⇒4a=c⇒4.1=c⇒c=4

Cl, left=2b, right=4+c⇒2b=4+c⇒2b=4+4⇒2b=8⇒b=4

The equation becomes :

CH₄ + 4Cl₂⇒  CCl₄+ 4HCl

3 0
3 years ago
Balance the following reaction. A coefficient of "1" is understood. Choose option "blank" for the correct answer if the coeffici
arlik [135]

The given reaction is:

C4H10 + O2 → CO2 + H2O

The above equation is not balanced due to the unequal distribution of atoms on either side of equation

# atoms Reactants           # atoms products

C = 4                                    C = 1

H = 10                                  H = 2

O = 2                                   O = 3

In order to balance it, multiply C4H10 by 2, O2 by 13, CO2 by 8 and H2O by 10 to get:

2C4H10 + 13 O2 → 8CO2 + 10H2O

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3 years ago
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