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Burka [1]
3 years ago
14

Ned is designing an experiment to test which hand sanitizer kills the most E. coli bacteria. In order for Ned's results to be va

lid, what must he do?
THE SUBJECT IS SCIENCE
Chemistry
2 answers:
sergiy2304 [10]3 years ago
4 0

Answer:

So the correct answer is "Test the hand sanitizers on bacterial colonies that are kept in the exact same environmental conditions, such as temperature and light level"

Explanation:

There are several ways to make sure the results of an investigation are valid. First, you and others can try to repeat the experiment. In addition, if it is a controlled experiment, you can make sure you have a control, only one independent variable, at least one dependent variable, and constants.

For Ned's results to be valid, he needs to test the hand sanitizers on bacterial colonies that are kept in the exact same environmental conditions, such as temperature and light level.

Molodets [167]3 years ago
3 0
Need more info please 
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Thank uuuu so much!!!!!
kow [346]

Answer:

A. 0.83

Explanation:

Hopefully this helps!

7 0
3 years ago
PLZ HELP!<br><br> How do you think changing the angle of a ramp will affect work done?
kogti [31]

Answer: The steepness of a ramp affects it by making it easier or harder.

Explanation: It's a bit situational. If you were going up a steep ramp with a heavy load, it will increase the work necessary, whereas if you were going down a ramp, it would decrease the work necessary. If you need this simply put, think about biking up and down a hill. It would be easier going down than up.

6 0
3 years ago
under certain water​ conditions, the free chlorine​ (hypochlorous acid,​ hocl) in a swimming pool decomposes according to the la
ivolga24 [154]

Answer:

1.7 ppm

Explanation:

Original amount N' = 2.6 ppm

time to testing t = 24 hr

final amount N = 2.1 ppm

Using exponential inhibited decay, we have

N = N'e^(-kt)

Where

N is the new reading

N' is the original reading

t is the decay time

k is the decay constant

Substituting, we have

2.1 = 2.6 x e^(-k x 24)

2.1 = 2.6 x e^(-24k)

0.808 = e^(-24k)

We take the natural log of both sides of the equation

Ln 0.808 = Ln (e^(-24k))

-0.213 = - 24k

K = 0.213/24 = 0.00886

After 48 hrs, the reading of free chlorine will be

N = 2.6 x e^(-0.00886 x 48)

N = 2.6 x e^(-0.425)

N = 2.6 x 0.654

N = 1.7 ppm

5 0
3 years ago
Calculate e°cell for a silver-aluminum cell in which the cell reaction is al(s) + 3ag+(aq) → al3+(aq) + 3ag(s) –2.46 v 0.86 v –0
tekilochka [14]
When E° cell is an electrochemical cell which comprises of two half cells.
 
So,

when we have the balanced equation of this half cell :

Al3+(aq) + 3e- → Al(s)   and E°1 = -1.66 V 

and we have  also this balanced equation of this half cell :

Ag+(aq)  + e- → Ag(s)  and E°2 = 0.8 V 

so, we can get E° in Al(s) + 3Ag (aq) → Al3+(aq) + 3Ag(s)

when E° = E°2 - E°1

∴E° =0.8 - (-1.66)

      = 2.46 V

∴ the correct answer is 2.46 V




6 0
4 years ago
If a container contains 3.5 moles and has a volume of 1.5 L, then what volume is it when it contains 8 moles? *
Lilit [14]
Volume would be 3.4 L
8 0
3 years ago
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