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konstantin123 [22]
3 years ago
11

Eva is performing an experiment to determine which type of disinfectant kills the most bacteria. She has six plates of the same

kind and amount of bacteria. She adds one of five different kinds of disinfectant to each plate and leaves one plate without any disinfectant as a control.
What role does the independent variable play in this experiment
A.
The type of disinfectant determines the amount of bacteria killed.
B.
The amount of bacteria killed determines the type of bacteria used.
C.
The type of disinfectant used determines the type of bacteria used.
D.
The amount of bacteria killed determines the type of disinfectant used.
Chemistry
2 answers:
Soloha48 [4]3 years ago
6 0

A is the one so she could spot the differnece with natural and the unnatrual decline

Flura [38]3 years ago
5 0

Answer:

A

Explanation:

I did it just now

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What is the potential energy of a molecule?
iren2701 [21]

Answer:

I guess the answer is D point

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2 years ago
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A box contains identical balls of which 12 are red, 18 white and 8 blue. Three balls are drawn from the box one after the other
svet-max [94.6K]

Answer:

a) 12/323

b) 8/233

Explanation:

a) The probability of a red ball being drawn is 12/38, or in a simplified fraction, 6/19. To find the probability that 3 are red you would multiply the probability of the fraction for each, except subtracting one from the total each time as the drawn is done without replacement. This is done as follows: 6/19 × 6/18 × 6/17= 12/323

b) The probability of drawing a blue ball is 8/38, or 4/19. To find that the first one is blue and the rest are red, the equation is done as follows: 4/19 × 6/18 × 6/17 = 8/233

(hopefully I did this right)

8 0
3 years ago
Mention any two factors that determines Cis/Trans Isomerization​
kenny6666 [7]

Answer:

1. There most not be rotation within the molecule.

2. Two non identical group must be present in the double bonded carbon atom.

Explanation:

This is because cis/ trans isomerism are that exhibit different structural configurations where the atoms are spartially arranged. They are also refered to as geometric isomers. They cannot be interconverted at room temperature because it requires the bonds to be broken and restructured.

Cis shows that the functional groups on present in the same side which trans isomerism show that the functional groups are on opposite sides.

6 0
3 years ago
a 100.0 g sample of a metal m is burned in air to produce 103.7 g of its oxide with the formula m2o. what is the atomic mass of
Ahat [919]
The molar mass should be 14.898g/mol. I used the equation 100gx(1/xg/mol)x(1mol/2mol)x(16g/mol+x)/1)=103.7 and solve for x. I found that equation using stoichiometry and the equation 2m+1/2O2-->m2O The molar mass of the metal I set to x and the molar mass of the metal oxide is 16+x.
6 0
3 years ago
What is the freezing point (in degrees Celcius) of 3.75 kg of water if it contains 189.9 g of C a B r 2?
blondinia [14]

Answer:

The freezing point of the solution is -1.4°C

Explanation:

Freezing point decreases by the addition of a solute to the original solvent, <em>freezing point depression formula is:</em>

ΔT = kf×m×i

<em>Where Kf is freezing point depression constant of the solvent (1.86°C/m), m is molality of the solution (Moles CaBr₂ -solute- / kg water -solvent) and i is Van't Hoff factor.</em>

Molality of the solution is:

-moles CaBr₂ (Molar mass:

189.9g ₓ (1mol / 199.89g) = 0.95 moles

Molality is:

0.95 moles CaBr₂ / 3.75kg water = <em>0.253m</em>

Van't hoff factor represents how many moles of solute are produced after the dissolution of 1 mole of solid solute, for CaBr₂:

CaBr₂(s) → Ca²⁺ + 2Br⁻

3 moles of ions are formed from 1 mole of solid solute, Van't Hoff factor is 3.

Replacing:

ΔT = kf×m×i

ΔT = 1.86°C/m×0.253m×3

ΔT = 1.4°C

The freezing point of water decreases in 1.4°C. As freezing point of water is 0°C,

<h3>The freezing point of the solution is -1.4°C</h3>

<em />

4 0
3 years ago
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