CHEMISTRY HIGH SCHOOL

How much of a sample remains after five half-lives have occurred?

Answers

Answer 1

Answer:

Answer: ${frac{1}{32}$

Explanation:

Half life is the time taken to reduce the original concentration of the reactants to half.

Now, the number of half lives is related to the amount left after decomposition by the formula:

$a=(a_o)/(2^n)$

where,

a = amount of reactant left after n-half lives = ?

$a_o$ = Initial amount of the reactant

n = number of half lives = 5

Putting values in above equation, we get:

$a=(a_0)/(2^5)$

$a=(a_0)/(32)$

Thus the amount of sample that remains after 5 half lives is $(1)/(32)$ of original amount.

Answer 2

Answer: It's exponential, every half life will multiply the amount by 1/2. After the first one, 1/2 After the second, 1/4, then 1/8, 1/16, and finally after the fifth will be 1/32.

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What is the role ofelectrons within an
atom?
A.
Electrons are in the nucleus and have a
negative charge
B. Electrons are in the nucleus and have a
positive charge
C. Electrons are outside the nucleus and
have a negative charge
D. Electrons are outside the nucleus and
have a positive charge

Answers

Option C - Electrons are outside the nucleus and and have a negative charge is the correct alternative.

We have electrons.

We have to determine their role inside the atom.

What are Electrons ?

An electron is one of the subatomic particles within an atom. It is negatively charged particle whose magnitude is 1.6 x 10⁻¹⁹ C.

According to the question -

The role of electrons inside the atom is as follows -

Electrons revolve around the nucleus.
They carry a negative - charge of -1.6 x 10⁻¹⁹ C.

Hence, Option C is the correct alternative.

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The answer would be “C” because electrons are found in the outer layer of an atom, and they are also negatively charged.

What does w represent

Answers

W is a variable that can be used to represent whole numbers or the first letter of an object in the problem. Example: If a house has 4 windows on each side and there’s 4 sides of the house, find W, or the amount of windows there are total. An example for how it could also be used as a whole number is: Find W in this problem, or the whole number. Hope this helps! :)

Answer:

It is used to represent whole numbers

Explanation:

Identify the effect of increasing acidity on the solubility of the given compounds.

Answers

An addition of acid increases the solubility of calcium phosphate because the hydrogen ions can easily dissociate and form salts. And example is from the reaction 3H2SO4 + Ca3(PO4)2 → 2H3PO4 + 3CaSO4. CaSO4 is the salt of sulfuric acid and calcium phosphate.

A mixture of sand and table salt can be separated by filtration because the substances in the mixture differ in( I) boiling point (2) density at STP(3) freezing point (4) solubility in water

Answers

A mixture of sand and table salt can be separated by filtration because the substances in the mixture differ in solubility in water. Thus, the correct option for this question is D.

What is meant by Solubility?

Solubility may be defined as the phenomenon in chemistry that involves the maximum amount of a substance that will significantly be disbanded in a given amount of solvent at a particular temperature.

The answer to the above question is better understood by the fact that when you mix both salt and sand in the water, you may find that salt is completely soluble in water while sand is not. This is because the bond of water is not competent enough to dissolve the sand.

Therefore, the correct option for this question is D.

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The answer is (4) solubility in water. When you put the mixture into water, the salt will dissolve and sand will not. The you can separated them by filtration will solution can pass through and sand will be left.

A mixture consists of sand and an aqueous salt solution. Which can be used to seperate the same, salt, and water from each other

Answers

The process which can be used to separate salt from the sand is leaching since salt is soluble in water thus it goes to the water leaving the sand behind. To separate salt from the water, you can allow the water to evaporate where it undergoes a phase change.

Calculate the ph and poh of a 0.0032 M solution of nitric acid NHO3