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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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Is this a chemical reaction?
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Answer:

I dont think so.

Explanation:

A chemical reaction is when there is a change in the substance. For example fizzing, bubbling, and changing colors are all examples of a chemical reaction.

5 0
3 years ago
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What is the function of a mordant in gram staining?
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5 0
3 years ago
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How many grams of a 23.4% by mass naf solution is needed if you want to have 1.33 moles of naf?
jenyasd209 [6]
Percentage by mass is the mass of NaF present in 100 g of the solution.
the percentage by mass of NaF is 23.4 %
this means that in 100 g of solution, mass of NaF present is 23.4 g
the number of moles of NaF present - 1.33 mol
mass of NaF - 1.33 mol x 42 g/mol = 55.9 g
when there's 23.4 g of NaF - mass of solution is 100 g
therefore when there's 55.9 g of NaF - mass of solution is 100 / 23.4 x 55.9 
= 239 g
mass of solution required is 239 g
6 0
4 years ago
How does the composition of a mixture of hydrogen and oxygen differ from the composition of a compound containing hydrogen and o
IrinaK [193]
Chemical compounds have chemically bonded molecules so that they exhibit different properties (i.e. chemical) compared to the individual molecules comprising the compound. Mixtures are simply the combinations of different molecules and compounds that are not chemically bonded together, and can therefore be separated by physical means. Mixtures usually retain the properties of its components. 

The hydrogen and oxygen molecules in a mixture do not form strong bonds between each other. The molecules of both gases are only contained in the same space or volume and the individual molecules retain their chemical properties. 

A compound containing hydrogen and oxygen molecules exhibit different chemical (and even physical) properties compared to the individual molecules themselves.

Water for example, is a compound with 2 hydrogen atoms and 1 oxygen atom, chemically-bonded together. Hydrogen gas is highly flammable, water is not. Oxygen gas is an essential reagent for combustion (or burning) reactions, water is not. 
 
Thus, throwing a lighted match to a gaseous mixture of hydrogen (H_{2}) and oxygen (O_{2}) would create fire, or even an explosion (since hydrogen is flammable and oxygen feeds the reaction). Throwing a match to water vapor (H_{2}O) would not create fire. 
5 0
4 years ago
Analysis of the water content of a lake found in the desert showed that it contained 16.6 percent chloride ion, and had a densit
IRISSAK [1]

Answer : The molarity of the chloride ion in the water is, 5.75 M

Explanation :

As we are given that 16.6 % chloride ion that means 16.6 grams of chloride ion present 100 grams of solution.

First we have to calculate the volume of solution.

\text{Volume of solution}=\frac{\text{Mass of solution}}{\text{Density of solution}}

\text{Volume of solution}=\frac{100g}{1.23g/mL}=81.3mL

Now we have to calculate the molarity of chloride ion.

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

\text{Molarity}=\frac{\text{Mass of chloride ion}\times 1000}{\text{Molar mass of chloride ion}\times \text{Volume of solution (in mL)}}

Now put all the given values in this formula, we get:

\text{Molarity}=\frac{16.6g\times 1000}{35.5g/mole\times 81.3mL}=5.75mole/L=5.75M

Thus, the molarity of the chloride ion in the water is, 5.75 M

8 0
3 years ago
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