A(n) ____________ is a substance in which all the exact combinations of elements are always the same.

Plutonium−239 (t1/2 = 2.41 × 104 yr) represents a serious nuclear waste hazard. if seven half-lives are required to reach a tole

dimulka [17.4K]

The half-life of Plutonium−239, t1/2 is 2.41 × 10⁴ yrs

time taken to reach tolerable level = seven half-lives
= 7 x t1/2
= 7 x 2.41 × 10⁴ yrs
= 168700 yrs
= 1.687 x 10⁵ yrs

Hence, the period of time that Plutonium-239 must be stored is 1.687 x 10⁵ years.

5 0

3 years ago

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What is bulimia? can someone explain it to me.

Charra [1.4K]

It is an emotional disorder involving distortion of body image and an obsessive desire to lose weight, in which bouts of extreme overeating are followed by depression and self-induced vomiting, purging, or fasting.The exact cause of bulimia is currently unknown; though it is thought that multiple factors contribute to the development of this eating disorder, including genetic, environmental, psychological, and cultural influences. Some of the main causes for bulimia include:
Stressful transitions or life changes
History of abuse or trauma
Negative body image
Poor self-esteem
Professions or activities that focus on appearance/performance

4 0

3 years ago

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Which series of atomic numbers represents the ordering of consecutive elements within the periodic table?

statuscvo [17]

Atomic number is same as the number of protons in the element which is further equal to the number of electrons. As the number of electrons increases in the element, the atomic number of the element also increases.

In periodic table, elements are arranged in the groups, and these groups are columns starting from 1 to 18, elements are arranged in increasing order of atomic number. Elements are placed with difference of one atomic number.

First four elements present in the periodic table is:

$He$ atomic number is one (1).

$H$ atomic number is two (2).

$Li$ atomic number is three (3).

$Be$ atomic number is four (4).

Thus, the series of atomic numbers that represents the ordering of consecutive elements within the periodic table is the last option - 1, 2, 3, 4...

4 0

3 years ago

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2.A calibration curve requires the preparation of a set of known concentrations of CV, which are usually prepared by dieting a s

Aleks04 [339]

Answer:

In order to prepare 10 mL, 5 μM; 2 mL of the 25 μM stock solution will be taken and diluted with water up to 10 mL mark.

In order to prepare 10 mL, 10 μM; 4 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 15 μM; 6 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 20 μM; 8 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

Explanation:

Using the dilution equation:

no of moles before dilution = no of moles after dilution.

Molarity x volume (initial)= Molarity x volume (final).

In order to prepare 10 mL, 5 μM from 25 μM solution,

Final molarity = 5 μM, final volume = 10 mL, initial molarity = 25 μM, initial volume = ?

25 x initial volume = 5 x 10

Initial volume = 50/25

= 2 mL

2 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 10 μM from 25 μM stock,

25 x initial volume = 10 x 10

Initial volume = 100/25 = 4 mL

4 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 15 μM from 25 μM stock,

25 x initial volume = 15 x 10

initial volume = 150/25 = 6 mL

6 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

In order to prepare 10 mL, 20 μM from 25 μM stock,

25 x initial volume = 20 x 10

initial volume = 200/25 = 8 mL

8 mL of the 25 μM stock solution will be taken and diluted up to 10 mL mark.

6 0

3 years ago

How can forgery be used in crime

Tems11 [23]

Some bad people will tend to forge dollar bills and make fake bills, giving them to cashiers and asking for it to be split into a different amount of bills so they are given real cash and wont be caught or they will buy things, return them and be given back real money and get away with it. This is obviously a crime because it's fake.

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2 years ago

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