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Tom [10]
2 years ago
7

A corpse discovered in the desert at 5:00 PM was found to have larvae from the blow fly species Phormia regina that had just dev

eloped into the first instar stage. Controlled experiments show that this species requires 16.0 hours at 26.7 ∘ C to develop from an egg to the first instar stage. The average nighttime temperature in the desert was 22.4 ∘ C , and the average daytime temperature was 37.8 ∘ C . If the sunset occurred at 9:00 PM and the sunrise occurred at 7:00 AM, how many hours prior to discovery was the corpse placed in the desert?
Chemistry
1 answer:
horrorfan [7]2 years ago
3 0

Answer:

12.19 hours prior to discovery was the corpse placed in the desert.

Explanation:

Heat required for fly eggs to develop into first instar larvae = Exposure\,time\times temperature

From the given,

Exposure time = 16 hrs

Temperature = 27 C

=16\times 27 = 427.2^{o}C

The day time exposed hours is 10 hrs.-(7.00am-5.00pm)

=10\times 37.8 = 378^{o}C

So, the extra heat  = 427.2-378= 49.2

The addition heat divided by average temperature.

Average temperature = 22.4 C

=\frac{49.2}{22.4}= 2.19 hrs

So, the total time exposed is night time hours to day time hours.

= 10+2.19 = 12.19 hrs.

Therefore, 12.19 hours prior to discovery was the corpse placed in the desert.

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When diluting the pickle juice food sample for titration, is it important to know the final volume exactly? Why or why not?
maks197457 [2]

Explanation:

When diluting a fruit juice, it is important to know the final volume so as not to over dilute the solution.

  • The fruit juice can become too diluted if we don't know the final volume .
  • Concentration refers to the amount of solute dissolved in a solvent.
  • To achieve a desired amount of concentration during dilution, the volume of the target must be known.
  • This will serve as a guide of the amount of solvent to add in order to take the solution to the desired volume.

Learn more:

Dilution brainly.com/question/11493179

#learnwithBrainly

3 0
2 years ago
Write equations that show the processes that describe the first, second, and third ionization energies for a gaseous iron atom.
Nikolay [14]
The ionization energy of an element is the amount of energy required to remove one mole of electrons from the element in its gaseous state. The equations for the first three are:

Fe(g) → Fe⁺(g) + e⁻

Fe⁺(g) → Fe⁺²(g) + e⁻

Fe⁺²(g) → Fe⁺³(g) + e

7 0
2 years ago
The average adult human burns 2.00x20^3 kcal per day in energy. What is this rate in kJ per hour?
IRISSAK [1]

Answer:

1.61 × 10⁶ kJ

Explanation:

The human burns energy so as to be healthy.

The amount of energy burnt per day by an adult human is 2 × 20³ kcal per day. Since there is 24 hours in a day, the amount of energy burnt per hour is 2 × 20³ × 24 = 48 × 20³ kcal per hour.

The conversion rate of kcal to kJ is 1 kcal = 4.184 kJ. Therefore converting the kcal per hour to kJ per hour gives:

48 × 20³ × 4.184 = 200.882 × 20³ kJ = 1.61 × 10⁶ kJ

7 0
2 years ago
calculate the water potential of a solution of 0.15m sucrose. the solution is at standard temperature.
Mrac [35]

Answer:

The water potential of a solution of 0.15 M sucrose solution is -3.406 bar.

Explanation:

Water potential = Pressure potential + solute potential

P_w=P_p+P_s

P_w=P_p+(-iCRT)

We have :

C = 0.15 M, T = 273.15 K

i = 1

The water potential of a solution of 0.15 m sucrose= P_w

P_p=0 bar (At standard temperature)

P_s=-iCRT=-\times 1\times 8.314\times 10^{-2}bar L/mol K\times 273.15 K=-3.406 bar

P_w=0 bar+(-3.406 ) bar

The water potential of a solution of 0.15 M sucrose solution is -3.406 bar.

7 0
2 years ago
Consider NH3 and PH3. Electronegativities: P = 2.1, H = 2.1, N=3.0. Which statement is false?
NikAS [45]

Answer:

The P-H bonds are more polar than the N-H bonds.

Explanation:

Phosphine is a polar molecule with non-polar bonds. The phosphorus atom is bonded to three hydrogen atoms and the phosphorus atom has a lone pair of electrons. Since hydrogen and phosphorus are equal in electronegativity, it implies that they attract the shared pairs of electrons the same amount,hence bonding electrons are shared equally making the covalent bonds non-polar.

The lone pair of electrons on phosphorus causes the molecule to be asymmetrical with respect to charge distribution this is why the molecule is polar even though the are non-polar bonds in the molecule.

Looking at the values of electro negativity stated in the question, one can easily see that the difference in electro negativity between nitrogen and hydrogen is 0.9 while the difference in electro negativity between phosphorus and hydrogen is zero. It is clear that NH3 is naturally more polar than PH3 since each individual N-H bond in NH3 is a polar bond while the individual P-H bonds in PH3 are nonpolar.

4 0
2 years ago
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