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In-s [12.5K]
3 years ago
14

Megan experimented with growing mold. She took 3 pieces of bread from the same loaf and placed each into a plastic sandwich bag.

Before sealing the bag, she added 5 drops of water to each slice. Next, she placed one bag on her window sill, one in a dark cabinet, and one in a room away from sunlight. Megan concluded that the different amount of mold that grew on each slice was due to the amount of light it received. Is this a valid conclusion?
A) Yes, because the light was the manipulated variable.


B) Yes, because the light was the controlled variable.


C) No, because the light could not have affected the growth.


D) No, because the light should have been the same for each bread slice.
Chemistry
2 answers:
kvasek [131]3 years ago
3 0

Answer:

Yes, because the light was the manipulated variable

Explanation:

djyliett [7]3 years ago
3 0

Answer:

Your answer would be A. Yes, because the light was the manipulated variable.

Explanation:

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What is the hybridization of the central atom, electron geometry, and molecular geometry of H3CCCH?
DIA [1.3K]

Answer:

Hybridization: sp

Electron geometry: linear

Molecular geometry: linear

Explanation:

H₃CCCH can also be written as its Lewis structure which is shown in the figure attached. The figure shows that the central carbon atom makes a single bond with CH₃ and a triple bond with CH. This means that the hybridization of the carbon is sp and both the electron and molecular geometry are linear with an 180° bond angle.

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How many simple distillation columns are required to purify a stream containing five components into five 'pure"products? Sketch
katen-ka-za [31]

Answer: one simple distillation column is required to separate the stream into five pure products. With four different flat bottom flask, for collection of the distilled products

Explanation: simple distillation works with the difference in boiling points of the liquid to be separated. For the separation of five different constituent to be possible, we have to know the boiling points of the constituents.

For your understanding, let's define constituents in the liquid to be A, B, C, D, E. And the boiling points increases respectively. Start by heating the liquid to the boiling point of A to extract A. After a while check if the constituents A is still dropping in the flat bottom flask, if it has stopped dropping, it simply means that we have extracted all A constituents in the liquid, label the Flask A. Get another flask to extract constituent B.

Heat the mixture to the boiling point of B, after a while check if constituent B is still dropping in the flat bottom flask, if it has stopped dropping,it means that we have extracted all B constituent in the liquid, label the Flask B. Get another flask for C.

Repeat the same process for C and D.

After Extracting D we don't need to distillate E because we already have a pure form of E inside to the conical flask.

SEE PICTURE TO UNDERSTAND WHAT A SIMPLE DISTILLATION LOOKS LIKE

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Question 6 (4 points)
pishuonlain [190]

Answer:

20.9%

Explanation:

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Substance A has the following properties.
givi [52]

A curve of temperature vs. time for the entire heating process.

The sample is heated up to 100.°C, therefore, the heat and time required to heat the sample to its boiling point, the heat and time required to boil the sample, and the heat and time required to heat the sample from its boiling point to 100.°C are needs to be calculated.

i ) Calculating the heat and time required to heat the sample to its boiling point:

Boiling point = 85°C

C(liquid) = 2.5 J/g °C

The heat required up to melting the sample is calculated in the previous parts. Therefore, the heat required to heat the sample from -20°C to 85°C can be calculated as,

Therefore, T f = 85°C  and T i = - 20°C

Plug in the values in the specific heat formula to calculate the heat energy required to heat the sample to its melting point,

q3 = 25 g ×  2.5 J/g °C × [85 - (-20)]°C

     = 25 J/°C ×[85+20]°C

     = 6562.5 J

The total heat energy required for heating the sample from initial temperature to boiling point is:-

q1 + q2 + q3 = 500 J + 4500 J + 6562.5 J

                    = 11562.5 J

The Rate of heating = 450 J/min

450. J = 1 min

   11562.5 J = ? min

11562.5 J × 1min/450 J = 25.69 min

ii) Calculating the heat and time required to boil the sample:

∆H Vap = 500 J/g

The boiling is the phase change from liquid to gas at 85°C, therefore, the heat required to boil the sample can be determined

q4= m × ∆Hvap

    = 25 g × 500 J/g

   = 12500 J

Thus, total heat required to this phase change is q1 + q2 + q3 + q4  = 500 J + 4500 J +6562.5  J + 12500 J = 24062.5 J

The Rate of heating = 450 J / min

450 J = 1 min

24062.5 J = ? min

24062.5J ×  1min / 450 J = 53.47 min

iii) Calculating the heat and time required to heat the sample from its boiling point to 100°C

C gas = 0.5 J / g °C

The heat required to boil the sample is calculated in the previous parts. Therefore, the heat required to heat the sample from 85°C to 100°C can be calculated as,

Therefore, T f = 100.°C  and T i = 85°C

q5 = 25 g ×  0.5 J / g °C × [100 - 85] °C

    = 25 J / °C ×15 °C

    = 187.5  J

The total heat energy required for heating the sample from initial temperature to 100°C is

q1 + q2 + q3 + q4 + q5 = 500 J + 4500 J + 2625J + 12500 J + 187.5 J

                                      =24250 J

The Rate of heating = 450 J / min

  450. J = 1 min

 24250 J=? min

Thus, heating the sample to 100.°C takes a total of 53.89 min.

iv) Draw a curve of temperature vs. time for the entire heating process:-

Temperature °C     Temperature K     Heat energy (J)     Time (min)

 -40 °C                       233                             0                     0

-20 °C                          253                          500                  1.11    

Melting -20 °C             253                        5000                   11.11

85 °C                         358                         11562.5              25.69

Boiling 85 °C             358                           24062.5          53.475              

100  °C                       373                             24250          53.89

Hence, the graph for the result is in the image.

Learn more about temperature here:-brainly.com/question/24746268

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4 0
1 year ago
Describe the structure of an Atom (HELP!)
Marat540 [252]

Answer:

The answer is A.

Explanation:

Neutrons and protons are located in the dense middle of the atom called the nucleus, and electrons are located on the electron cloud located outside of the nucleus.

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