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dmitriy555 [2]
3 years ago
7

Question 13 (3 points)

Chemistry
1 answer:
Inessa05 [86]3 years ago
6 0
The answer is the D. "Observation" is not a variable in an experiment.
Explanation: Research variables are factors that can be manipulated, measured or those that we try to explain through other variables. "Observation" is not a variable in an experiment, but it is the first step and fundamental part in the scientific method, in which the experiments are contained (experimentation stage). Observation is the information recorded during an experiment, obtained through the senses or through the registration of information on scientific instruments.
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Which organelles do plant cells have that animal cells do not have?
velikii [3]
Plant cells have chloroplasts and a cell wall..... chloroplasts are the organelle that conduct photosynthesis..... and the cell wall is like an extra barrier for the cell membrane.... I hope this helps, have an amazing day/or night.... and god bless uuuu!!!

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4 0
3 years ago
Read 2 more answers
How many miles of NaCl are in 250 mL of a 0.4 M solution?​
creativ13 [48]

Answer:

There are 0.1 moles of solute in 250 mL of 0.4 M solution.

Explanation:

First, recognize that the molar concentration tells you how many moles of the solute are present in one liter of solution. In a 0.4 M solution, there are 0.4 moles of solute in every liter of solution. You can determine the number of moles of solute in 250 mL of the solution using dimensional analysis.

250 ml . 1L/1000 L . 0.4mol / 1L

Units of liters and milliliters cancel, leaving you with a final answer in units of moles, at 0.1 mol.

8 0
3 years ago
Determine the empirical formula of kevlar, used in making bullet proof vests, is 70.6% c, 4.2% h, 11.8% n and 13.4% o.
Likurg_2 [28]

Assuming a basis of 100 g of Kevlar, therefore the masses are:

C = 70.6 g

H = 4.2 g

N = 11.8 g

O = 13.4 g

 

We know the molar masses are:

C = 12.01, H = 1.008, N = 14.01, O = 16.00

 

Calculating for the moles per element:

C = 70.6 / 12.01 = 5.88 mol

H = 4.2 / 1.008 = 4.17 mol

N = 11.8 / 14.01 = 0.84 mol

O = 13.4 / 16 = 0.84 mol

 

To get the empirical formula, the next step is to divide everything by the smallest moles = 0.84. So:

C = 7

H = 5

N = 1

O = 1

 

Hence the empirical formula is:

C7H5NO

3 0
4 years ago
In an experiment, a solution required 30. 05 g of nacl, 50. 0 g of , and 0. 4006 g of mgso4. Using the correct number of signifi
Radda [10]

When the use of significant figures and rounding up is applied correctly the mass of the mixture will be 80.5 g.

In cases of addition or subtraction, only the last significant figure of every number is taken into account.

In 30.05, this is 5, in the hundredths. When we look at 50.0, the last significant figure is 0, and it is in the tenths. And in 0.4006, the last significant figure is 6, in the ten thousandths. Of these three, the 0 from 50.0 is in the leftmost position, which means that the last significant figure of the result needs to be in the same position (in the tenths).

Moving onto the actual algebraic operation:

30.05 g + 50.0 g + 0.4006 = 80.4506 g

As we established, the last significant figure should be in the tenths, and we will have to round up 4 to 5 (trailing numbers are greater than 0), which means that the resulting mass will be 80.5 g.

You can learn more about significant figures here:

brainly.com/question/14804345

#SPJ4

7 0
2 years ago
**<br> H₂ + O2-&gt;<br> Balancing equations from a reaction
goblinko [34]

Answer:

2H2+O2->2H2O

Explanation:

You have to balance the equation, you have 4 hydrogen and 2 oxygen atoms

8 0
3 years ago
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