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kirill115 [55]
3 years ago
9

A sample of polonium-210 has an initial mass of 390 milligrams (mg). If the half-life of polonium-210 is 36 days, how many mg of

the sample remains after 72 days?
A.
392 mg

B.
195 mg

C.
97.5 mg

D.
48.75 mg
Chemistry
2 answers:
kondaur [170]3 years ago
5 0

Answer: D. 48.75

Explanation: just took the test

maw [93]3 years ago
5 0

Answer:

D

Explanation:

I got this question right on my test.

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What is the name of the following compound? A line-angle formula shows a ring with six vertices and a circle inscribed. A Cl ato
ozzi

Answer: Option C. p-dichlorobenzene and 1,4-dichlorobenzene.

Explanation:

A line-angle formula with six vertices and a circle inscribed corresponds to the compound known as benzene.

Further, according to the IUPAC standards for naming benzene derivatives, you must first number the position of the substituent. In this case, the substituents (chloros) are located at the positions 1 and 4; also, for the benzene derivatives when they have 2 substituents and the positions are 1 and 4, this configuration is known as <em>para </em>or <em>p </em>configuration.

Additionally, this compound has 2 substituents (chloros) so you have to indicate this number (di).

Therefore, the correct answer is C. p-dichlorobenzene and 1,4-dichlorobenzene.

4 0
3 years ago
Calculate the mole fraction of kbr (molar mass 119.00 g/mol) in a solution made by dissolving 0.30 g kbr in 0.400 l of H2O (d =
julia-pushkina [17]

The mole fraction of KBr in the solution is 0.0001

<h3>How to determine the mole of water</h3>

We'll begin by calculating the mass of the water. This can be obtained as follow:

  • Volume of water = 0.4 L = 0.4 × 1000 = 400 mL
  • Density of water = 1 g/mL
  • Mass of water =?

Density = mass / volume

1 = Mass of water / 400

Croiss multiply

Mass of water = 1 × 400

Mass of water = 400 g

Finally, we shall determine the mole of the water

  • Mass of water = 400 g
  • Molar mass of water = 18.02 g/mol
  • Mole of water = ?

Mole = mass / molar mass

Mole of water = 400 / 18.02

Mole of water = 22.2 moles

<h3>How to de terminethe mole of KBr</h3>
  • Mass of KBr = 0.3 g
  • Molar mass of KBr = 119 g/mol
  • Mole of KBr = ?

Mole = mass / molar mass

Mole of KBr = 0.3 / 119

Mole of KBr = 0.0025 mole

<h3>How to determine the mole fraction of KBr</h3>
  • Mole of KBr = 0.0025 mole
  • Mole of water = 22.2 moles
  • Total mole = 0.0025 + 22.2 = 22.2025 moles
  • Mole fraction of KBr =?

Mole fraction = mole / total mole

Mole fraction of KBr = 0.0025 / 22.2025

Mole fraction of KBr = 0.0001

Learn more about mole fraction:

brainly.com/question/2769009

#SPJ1

6 0
2 years ago
____________ enables you to ride a bike without skidding and falling.
Marina86 [1]
Sliding or rolling friction
4 0
3 years ago
To calculate acceleration you must know both the objects velocity and _______________ 1pt
KATRIN_1 [288]

Answer:

i think its speed

Explanation:

8 0
3 years ago
Read 2 more answers
Need help plz help any one
dimulka [17.4K]
Hi!

Composition: the way in which a whole is made up

Hope I helped!
Have a nice day!
6 0
3 years ago
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