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bulgar [2K]
3 years ago
11

If an athlete runs at a speed of 12.9 km/hour, how long will it take the athlete to run a marathon (about 42.2 km)? Express your

answer in hours using the correct number of significant figures. Do not enter your answer using scientific notation.
Chemistry
1 answer:
jekas [21]3 years ago
7 0

Answer:

Time = 3.27s

Explanation:

Time = Distance / Speed

Time = 42.2 / 12.9 = 3.2713

When you multiply the number of significant figures in the result is the same as the number with the least significant figures.

In this case 42.2 has 3 significant figures and 12.9 also has 3 significant figures, therefore the answer must have 3 significant figures too.

Time = 3.27 s

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2 years ago
Draw the structure of the following atoms<br> (1) 19/9 F<br> (2)28/14 SI
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3 years ago
The human eye has an osmotic pressure of 8. 00 atm at 37. 0 °c. what concentration (in moles/l) of a saline (nacl) solution will
Gelneren [198K]

0.3147 concentration (in moles/l) of a saline (NaCl) solution will provide an isotonic eyedrop solution.

Isotonic eye drops

Because it might result in eye discomfort or tissue damage if it is not maintained, isotonicity is regarded as a crucial component of ophthalmic medicines. A few drops of blood are mixed with the test preparation before being examined and judged under a microscope at a magnification of 40. Isotonic solutions are those that have the same amount of water and other solutes in them as the cytoplasm of a cell. Since there is no net gain or loss of water, placing cells in an isotonic solution will not cause them to either shrink or swell.

We can calculate the osmotic pressure exerted by a solution using the following expression.

π = M . R . T

where,

π is the osmotic pressure

M is the molar concentration of the solution

R is the ideal gas constant

T is the absolute temperature

The absolute temperature is 37 + 273 = 310 K

π = M . R . T

8 = (X mol/L) . (0.082atm.L/mol.K) . 310 K = 0.3147 mol/L

To learn more about osmotic pressure refer:

brainly.com/question/5041899

#SPJ4

7 0
2 years ago
How do ozone molecules form in the stratosphere?
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Sunlight breaks apart an oxygen molecule to form separate oxygen atoms <span />
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3 years ago
What is the energy change if 84.0 g of calcium oxide (CaO) reacts with excess water in the following reaction?
pochemuha
   The energy change  if 84.0 g   of CaO  react  with  excess  water is  98KJ of heat is released.

calculation
heat  =  number of moles  x  delta H

delta H = - 65.2  Kj/mol

first find the number of  moles  of  CaO reacted

moles = mass/molar mass
the molar mass  of CaO =  40 +  16=  56 g/mol
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moles therefore = 84 g/56 g/mol =1.5 moles

Heat is therefore =  1.5 moles  x -65.2 = - 97.8 Kj = -98 Kj

  since  sign is  negative  the   energy  is released 

6 0
3 years ago
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