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Harman [31]
3 years ago
5

Please help me with these questions I don't get science

Chemistry
2 answers:
ipn [44]3 years ago
6 0

There are at least 60 elements in our bodies.

Other elements may be present, but in such small quantities that we cannot detect them with current technologies.

The six most abundant elements (by mass) in our bodies are:

Oxygen           65    %

Carbon            18    %

Hydrogen       10    %

Nitrogen          3.2 %

Calcium           1.4 %

Phosphorus    <u>1.1  % </u>

TOTAL =      99     %

LiRa [457]3 years ago
4 0
Proteins are made of carbon, hydrogen,oxygen, and nitrogen (CHON). Nucleic acids such as DNA and RNA contain carbon,hydrogen, oxygen, nitrogen, and phosphorus(CHON P). The body also needs trace amounts of other elements such as calcium,potassium, and sulfur for proper functioning of muscles, nerves, etc.
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The following data was collected when a reaction was performed experimentally in the laboratory.
Lera25 [3.4K]

Answer:

Mass = 279.23 g

Explanation:

Given data:

Number of moles of Fe₂O₃ = 3 mol

Number of moles of Al = 5 mol

Maximum amount of iron produced by reaction = ?

Solution:

Chemical equation:

Fe₂O₃ + 2Al    →     Al₂O₃  +  2Fe

Now we will compare the moles of iron with Al and iron oxide.

                          Fe₂O₃     :       Fe

                             1           :        2

                             3          :       2×3 = 6 mol

                            Al          :          Fe

                              2         :           2

                               5        :           5 mol

The number of moles of iron produced by Al are less so Al is limiting reacting and it will limit the amount of iron so maximum number of iron produced are 5 moles.

Mass of iron:

Mass = number of moles × molar mass

Mass =   5 mol  ×  55.845 g/mol

Mass = 279.23 g

 

3 0
3 years ago
How many grams of Kr are in a 9.59 L cylinder at 46.0 'C and 4.62 atm?<br> mass:
Sladkaya [172]

Answer:

Mass = 141.6 g

Explanation:

Given data:

Mass of Kr in gram =  ?

Volume in L = 9.59 L

Temperature = 46.0°C

Pressure = 4.62 atm

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will convert the temperature.

46.0+273 = 319 K

4.62 atm × 9.59 L = n× 0.0821 atm.L/ mol.K  ×319 K

44.3 atm.L = n×26.19 atm.L/ mol

n = 44.3 atm.L / 26.19 atm.L/ mol

n = 1.69 mol

Mass in gram:

Mass = number of moles × molar mass

Mass = 1.69 mol × 83.79 g/mol

Mass = 141.6 g

8 0
3 years ago
What is one major purpose for an animal to produce unusual sounds, display bright
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The weak type of bonding which attracts molecules to molecules is:
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B. Hydrogen is the answer
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1. Which of the following is an SI base unit for time? (2 points)
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