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3 years ago

Please help me :)))))))))))))))))))))))))))))))))

Chemistry

1 answer:

saw5 [17]3 years ago

8 0

Answer:

element is the 4th one

02 is the 3rd one

C02 is the 2nd one

atom is the 1st one

Explanation:

hope this helps you :)

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ddd [48]

They are both small and makeup everything in life

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3 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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3 0

2 years ago

Please help, due tomorrow! ツ

oksano4ka [1.4K]

There are two kinds of mixtures

a) homogeneous : the boundary of the two components is not physically distinct

b) heterogeneous:the boundary of the two components is physically distinct

the following separation techniques are common for mixtures

1) filtration: if the two components are forming heterogeneous mixture we can separate them by filtration.

2) boiling: if boiling point of one of the components is less than other

3) magnetic separation: if one of the component is magnetic

4)sieve method: for solid components with difference in size of particles

5) hand picking

Thus the correct match will be as shown in the figure

3 0

3 years ago

Give reasons. 1. There is interrelation between wildlife and vegetation 2. Various activities of the man have helped for the sur

nikitadnepr [17]

Answer:

Yes

Explanation:

4 0

3 years ago

A well-known scientist testifies that she believes a piece of evidence is accepted by science. The judge rules that the evidence

notsponge [240]

Answer:

The correct answer is C:

Kumho Tire Co. Ltd V. Daubert

Explanation:

In this case, the appellant (Daubert) has sued Kumho Tire Co. Ltd (the defendant) when 3 months prior the right rear tyre of his car exploded while the car was in motion killing a passenger and injuring others severely.

The appellant employed the services of an expert who had worked for 10 years with Michelin to give his opinion as having studied the attributes of the tire technology.

In a counter-argument, the defendant rather than dispute the opinion of the expert urged the court to exclude it as evidence because his methodology didn't conform to the requirements of the Law as given in Rule 702 of the Federal Rules of Evidence.

True to the defendants' position, the Law by the ruling in Daubert v Merrell Dow Pharmaceuticals required that for the opinion to count, it had to be scientifically correct. It was hence excluded as evidence in the case.

Cheers!

5 0

4 years ago