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olya-2409 [2.1K]
3 years ago
11

When Mendeleev started his work on organizing the elements, about how many had

Chemistry
1 answer:
Talja [164]3 years ago
8 0

Answer:

About 60.

Explanation:

Mendeleev knew of 63 elements. He wrote their properties on cards and arranged them in order of atomic mass.

That's how he discovered that the properties of elements are periodic functions of their atomic masses.

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PLEASE HELP URGENT ( photo included)
elena-14-01-66 [18.8K]

Answer:

B

Explanation:

4 0
3 years ago
8. A 220 mL sample of helium gas is in a cylinder with a movable piston at 105 kPa and 275K. The piston
Harrizon [31]

The sample has a new pressure of 274kPa. If at 105 kPa and 275K, a 220 mL sample of helium gas is contained in a cylinder with a moving piston. The sample is pushed till it has a 95.0 mL volume and 310K .

The macroscopic characteristics of ideal gases are related by the ideal gas law (PV = nRT). A gas is considered to be perfect if its particles (a) do not interact with one another and (b) occupy no space (have no volume). Where P= pressure  V= volume and T = temperature.

From ideal gas equation

P₁V₁/T₁ =P₂V₂/T₂

105×220÷275 = P₂ ×95÷310

P₂= (105×220×310)÷(275×95)

P2= 7161000/26125

P2 = 274.105 kPa

Hence, the new pressure of helium gas is 274kPa

To know more about Ideas gas equation

brainly.com/question/28837405

#SPJ1

8 0
1 year ago
A mixture of hydrogen and argon gases is maintained in a 6.47 L flask at a pressure of 3.43 atm and a temperature of 85 °C. If t
11Alexandr11 [23.1K]

Answer:

The mixture contains 8.23 g of Ar

Explanation:

Let's solve this with the Ideal Gases Law

Total pressure of a mixture = (Total moles . R . T) / V

We convert T° from °C to K → 85°C + 273 = 358K

3.43 atm = (Moles . 0.082 L.atm/mol.K . 358K) / 6.47L

(3.43 atm . 6.47L) / (0.082 L.atm/mol.K . 358K) = Moles

0.756= Total moles from the mixture

Moles of Ar + Moles of H₂ = 0.756 moles

Moles of Ar + 1.10 g / 2g/mol = 0.756 moles

Moles of Ar = 0.756 moles - 0.55 moles H₂ → 0.206

We convert the moles to g → 0.206 mol . 39.95 g / 1 mol = 8.23 g

8 0
3 years ago
Read 2 more answers
H202-h20-o2<br> In this process oxygen gas is a
Advocard [28]

Answer:

Oxgeyn gas liquid.

Explanation:

6 0
3 years ago
It's normal for climates to change naturally over time.
creativ13 [48]

<u>Answer:</u>

Earth's climate has changed naturally over the past 650,000 years, moving in and out of ice ages and warm periods. Changes in climate occur because of alterations in Earth's energy balance, which result from some kind of external factor or "forcing" an environmental factor that influences the climate.

<u />

<u>Explanation:</u>

*Hope this helps*

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7 0
3 years ago
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