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Maslowich
3 years ago
8

Which of the following is an example of a chemical change?

Chemistry
2 answers:
Lynna [10]3 years ago
6 0
The answer is burning paper

svetoff [14.1K]3 years ago
4 0
Burning paper...chemical changes are permanent and can't return to original form.<span />
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Can somebody help me, please!
zavuch27 [327]

Answer:

Rubidium-85=61.2

Rubidium-87=24.36

Atomic Mass=85.56 amu

Explanation:

To find the atomic mass, we must multiply the masses of the isotope by the percent abundance, then add.

<u>Rubidium-85 </u>

This isotope has an abundance of 72%.

Convert 72% to a decimal. Divide by 100 or move the decimal two places to the left.

  • 72/100= 0.72      or        72.0 --> 7.2 ---> 0.72

Multiply the mass of the isotope, which is 85, by the abundance as a decimal.

  • mass * decimal abundance= 85* 0.72= 61.2

Rubidium-85=61.2

<u>Rubidium-87</u>

This isotope has an abundance of 28%.

Convert 28% to a decimal. Divide by 100 or move the decimal two places to the left.

  • 28/100= 0.28       or        28.0 --> 2.8 ---> 0.28

Multiply the mass of the isotope, which is 87, by the abundance as a decimal.

  • mass * decimal abundance= 87* 0.28= 24.36

Rubidium-87=24.36

<u>Atomic Mass of Rubidium:</u>

Add the two numbers together.

  • Rb-85 (61.2) and Rb-87 (24.36)
  • 61.2+24.36=85.56 amu
4 0
3 years ago
It was observed that magnesium sulphate was present in tap water ,which hardness might that be​
astraxan [27]

Answer:

Calcium sulphate is the right answer for this question.

It is because calcium sulphate helps to obtain the hardness in water. hardness.

The presence of this resource is a main reason for permanent hardness.

Hard drinking water has moderate health benefits, but can pose serious problems for the industrial settings.

Explanation:

8 0
2 years ago
Fire extinguishers that spray carbon dioxide on the fire, work very effectively because it forms a blanket around the burning ma
Arte-miy333 [17]

Answer:

I think it will option B it will retain enough heat

8 0
3 years ago
The following thermochemical equation is for the reaction of Fe 3 O 4 (s) with hydrogen (g) to form iron and water vapor Fe 3 O
Mila [183]

Answer:

41.3kJ of heat is absorbed

Explanation:

Based in the reaction:

Fe₃O₄(s) + 4H₂(g) → 3Fe(s) + 4H₂O(g) ΔH = 151kJ

<em>1 mole of Fe3O4 reacts with 4 moles of H₂, 151kJ are absorbed.</em>

63.4g of Fe₃O₄ (Molar mass: 231.533g/mol) are:

63.4g Fe₃O₄ × (1mol / 231.533g) = <em>0.274moles of Fe₃O₄</em>

These are the moles of Fe₃O₄ that react. As 1 mole of Fe₃O₄ in reaction absorb 151kJ, 0.274moles absorb:

0.274moles of Fe₃O₄ × (151kJ / 1 mole Fe₃O₄) =

<h3>41.3kJ of heat is absorbed</h3>

<em />

6 0
3 years ago
How many molecules are in 5.60 L of oxygen gas
topjm [15]
5.6L of O2 means we have 0.25 moles of O2.
As, 1 mole has 6.023*10^23 molecules,
0.25 moles of O2 will have 0.25*6.023*10^23 molecules=1.50575*10^23 molecules
and as 1 molecule of O2 has 2 atoms, so, 1.50575*10^23 molecules will have 2*1.50575*10^23 atoms=3.0115*10^23 atoms of O.
3 0
3 years ago
Read 2 more answers
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