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steposvetlana [31]
3 years ago
5

Which of the following isotopes is radioactive A)C-12 B)Pb-206 C) Tc-99 D)Ne-20

Chemistry
1 answer:
Gre4nikov [31]3 years ago
4 0
C) Tc-99 is a radioactive isotope also known as radioisoptope. 
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Which best describes the relationship between the terms frequency, wavelength, and hertz?
Oksanka [162]

Answer:

The correct answer is - Frequency is the number of wavelengths, which is measured in hertz.

Explanation:

Frequency is the number of waves that go through a fixed point at a particular time. Hertz is the SI unit for frequency which means that one hertz is equal to a unit number of waver passes in a unit time to a fixed point.

As the frequency of a wave increases which means the number of waves increases in the unit time, the shorter the wavelength will be.

a higher frequency wave has more energy than a lower frequency wave with the same amplitude.

5 0
3 years ago
How many moles are in 4.3 x 10 ^22 molecules of Na3PO4
Sever21 [200]

Answer:

0.071 moles of Na₃PO₄ .

Explanation:

Given data:

Number of molecules of Na₃PO₄ = 4.3× 10²² molecules

Number of moles = ?

Solution:

1 mole contain 6.022 × 10²³ molecules

4.3× 10²² molecules × 1 mol / 6.022 × 10²³ molecules

0.71× 10⁻¹ mol

0.071 mol

The number 6.022 × 10²³ is called Avogadro number.

"It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance"

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3 years ago
When two ionic compounds are dissolved in water, a double replacement reaction can... Group of answer choices occur if two of th
sergey [27]

Answer:

occur if two of the ions form an insoluble ionic compound, which precipitates out of solution

Explanation:

When two ionic compounds are dissolved in water, a double replacement reaction takes place if two of the ions form an insoluble ionic compound, which precipitates out of solution. In double displacement reaction ions switch partners. And hence, produce an insoluble precipitate.

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Monica wrote the following observations about stars: "I observed a pattern of five stars at 8:00 p.m. and again at 9:00 p.m. The
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The answer would be b
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A.) Aluminum is the correct answer
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