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2 years ago

Define density please thanks!!

Chemistry

1 answer:

Lera25 [3.4K]2 years ago

5 0

the degree of compactness of a substance.

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4 years ago

You start out with 800 moles of a radioactive substance. After 24 hours, 100 moles remain. What is the half-life of the substanc

Nookie1986 [14]

The half life of the substance is 8 hours , Option D is the correct answer.

What is Half Life ?

Half-life is the time required by an unstable element to reduce to half of its initial value.

The term is commonly used in nuclear physics.

The formula is

$\rm N(t) = \; N_{0} \;(\dfrac{1}{2} )^{\frac{t}{t_{1/2} } }$

N(t) = quantity of the substance remaining

N ₀ = initial quantity of the substance

t = time elapsed

$\rm t_{1/2}$ = half life of the substance

The data given in the question is N ₀ = 800 moles , N(t)= 100 , t= 24 hours

$\rm t_{1/2} =\; ?$

Substituting values in the equation

$\rm 100 = \; 800 \;(\dfrac{1}{2} )^{\frac{24}{t_{1/2} } }$

$\rm \dfrac{100}{800} = \;(\dfrac{1}{2} )^{\frac{24}{t_{1/2} } }\\\\\rm \dfrac{1}{8} = \;(\dfrac{1}{2} )^{\frac{24}{t_{1/2} } }\\\\\rm (\dfrac{1}{2})^{3} = \;(\dfrac{1}{2} )^{\frac{24}{t_{1/2} } }\\\\\rm 3=\dfrac{24}{t_{1/2} }\\\\t_{1/2}= \dfrac{24}{3}\\\\t_{1/2} = 8 hours$

Therefore half life of the substance is 8 hours , Option D is the correct answer.

To know more about Half Life

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2 years ago

What do the rows of the periodic table indicate?

Tanya [424]

Answer:

The rows on the periodic table are called periods. All the elements in a period have valence electrons in the same shell. The number of valence electrons increases from left to right in the period. When the shell is full, a new row is started and the process repeats.

Explanation:

hope this helps..

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3 years ago

Luke recorded his results in a table as shown below.

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3 years ago

never [62]

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The answer to your question is probably false

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