Help please I don’t know what to do

Answer:

How long has this blood been here?

Explanation:

Answer:

Leslie is a forensic scientist who is using the precipitin test at a crime scene. What question is Leslie MOST likely trying to answer?

Explanation:

Leslie is a forensic scientist who is using the precipitin test at a crime scene. What question is Leslie MOST likely trying to answer? got the answer from quilt

Potassium has a lower EN than Bromine.

EN Trends:

Decreases down the group but increases across a period.

Potassium is to the left of the periodic table while bromine is on the right, and according to the trends, Bromine will be bigger because EN increases across a period. This allows the nucleus to attract the bonding electrons more strongly.

Hope it helps!

Answer:

17.19%

Explanation:

mass of oxygen = 7.221 - (1.990 + 2.341)

= 2.890g

Empirical formula of the compound

For carbon,

1.990/12 = 0.1658

For hydrogen,

2.341/1 = 2.341

For oxygen,

2.890/16 = 0.1806

0.1658 ÷ 0.1658 = 1

2.341 ÷ 0.1658 = 14.11

0.1806 ÷ 0.1658 = 1.089

Empirical formula of the compound= CH14O

Molar mass= (1×12) + (14×1) + (1×16)

= 12+14+16

= 42g/mol

percentage composition= 7.221/42 × 100

= 17.19%

the answer is A. SnCl2 . 2H2O

Answer:

True

Explanation:

the empirical formula usually shows us the atoms' symbols and then how much of them are present in this certain compound. For example there is H2O

Answer:

2: 2.02 x 1024 atoms

3: 4.5201 atoms

4: 384 g/mol

Explanation: I'm in your class

Explanation:

a particle smaller than an atom (e.g., a neutron) or a cluster of such particles (e.g., an alpha particle).

Answer:

Boyle's most famous discovery had to do with how the pressure and volume of gases relate, either this or he discovered the volume of a gas decreases with increasing pressure...

Explanation:

...

Answer:

Hydrogen, hope this helps :)

Answer:

A

Explanation:

Answer:

the sun is directly behind your head

Explanation:

The reason why we can see a rainbow is caused by sunlight and atmospheric conditions

A GEL is a semisolid preparation that contains very small solid particles that are suspended in a liquid. A gel always contains an agent (e.g., agarose) that provides stiffness to the preparation.

A gel is a semisolid preparation that contains a gelling agent which provides stiffness to the preparation.

The gelling agent can be, for example, agarose (this gelling agent is used to prepare gels in electrophoresis).

In an agarose gel, agarose molecules are organized into three-dimensional (3D) structures similar to pores, which allow the passage of DNA fragments during electrophoresis.

Learn more about agarose gel here:

https://brainly.com/question/5661562

This question is asking for the correct balanced reaction, when solid aluminum reacts with gaseous oxygen to form solid aluminum oxide, according to the law of conservation of mass, which demands us to have the same number of atoms of each element on both sides of the equation.

In such a way, we can start by knowing there is one aluminum atom on the left and two on the right whereas there are two oxygen atoms on the left and three on the right side of the equation.

The aforementioned means we must balance oxygen first by putting a 2 on aluminum oxide and a 3 on oxygen in order to cross multiply and obtain six oxygen atoms on both sides of the equation.

Moreover, the 2 on the aluminum oxide makes four aluminum atoms on the right, which means we must put a 4 on the left-handed aluminum in order to get the correct balance, and therefore, write the following balanced equation:

4Al(s) + 3O₂(g) ⇒ 2Al₂O₃(s)

Hence, the coefficient for Al, as asked, is 4.

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This problem is providing describing a room in which air has a total pressure of 0.987 atm and the partial pressure of nitrogen is asked, turning out to be 0.746 atm.

In such a case, we can start by looking at the provided table, which shows the composition of dry air in mass basis, which means we must convert the composition of nitrogen to mole fraction by knowing that the average molar mass of air is 28.9647 g/mol, and thus, we infer that the mole fraction of nitrogen in air is about 0.755 according to:

[tex]x_{N_2}=\frac{0.781*14.0067g/mol*2}{28.9647g/mol} =0.755[/tex]

Then, we recall the Dalton's law version that relates total pressure, partial pressure and mole fraction written for nitrogen:

[tex]P_{N_2}=x_{N_2}P[/tex]

Finally, we plug in the previously calculated mole fraction and the total pressure of air to obtain:

[tex]P_{N_2}=0.755*0.987 atm\\\\P_{N_2}=0.746atm[/tex]

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Answer:

C

Explanation:

The molecular formula of the ethylene glycol is C₂H₆O₂.

From the question given above, the following data were obtained:

Molecular formula = empirical × n = molar mass

[CH₃O]n = 62

[12 + (3×1) + 16]n = 62

31n = 62

Divide both side by 31

n = 62 / 31

n = 2

Molecular formula = [CH₃O]n

Molecular formula = [CH₃O]₂

Molecular formula = C₂H₆O₂

Learn more about empirical and molecular formula: https://brainly.com/question/25820990

Answer:

A. Na+ OH-

Explanation:

positive and negative ions form bonds because positive and negative attract

Answer:

B

Explanation:

Answer:

B. compound

Explanation:

A pure substance can be an element, which consists of only one type of atom and cannot be broken down by a chemical change, or a compound, which consists of two or more types of atoms.

Answer:

#1 is C, #2 is D, #3 is A

Explanation:

Answer:

at their own state.

That leaves only five elements: carbon, phosphorus, sulfur, selenium, and iodine, which are all non-metals and are solid at room temperature.

Answer:

14.54 g Fe2O3

Explanation:

The first step would be to balance the equation but since it's already balanced we don't have to worry about that.

Through the balanced equation, you can find the stoichiometry of the reaction, that is:

4 moles of Fe, react with 3 moles of O2, to produce 2 moles of Fe2O3

Chemistry (accurately stoichiometry) is all about ratios and proportions. The balanced equations gives you the standard ratio by which moles are produced.

So the next step (shown in the paper), is to convert the grams that are giving you in Moles, and you do this by dividing the number of grams given by the molar mass of the substance. The molar mass is the number of grams by which you can find exactly 6.022x10²³ molecules (one mole) of one specific substance.

15.4 g of Fe= 0.28 mol Fe

3.6 g of O2= 0.11 mol O2

Now that you have the quantity of moles, what you need to do is to look for the limitant reactant.

In a balanced equation, the number of moles in the reactants are the rules and they're gonna react completely with each other. If you want x quatity of reactants to react completely, then you will have to respect the proportion to the ratio given in the balanced equation.

But you will rarely follow the proportion so there will usually be a reactant that's gonna be limiting the reaction and one that is in excess. And how do you find this? Well, the easiest way to do it is:

Since the limitant reactant is gonna be limiting the reaction, all the stoichiometric procedures should be calculated through it, and in this case, the limitant reactant is O2.

But then how to establish the stoichiometric rule to find the number of Iron oxide (III) that's being produced?

Look back to the stoichiometry of the reaction:

To produce 2 moles of Fe2O3, you need 3 moles of O2.

But you have 0.11 mol O2.

Then establish a factor of conversion (shown in the picture)

The result is 0.07 mol of Fe2O3, but you need the answer in grams so you find the molar mass of Fe2O3 and then multiply it by the number of moles (0.07)

The answer is 14.54 g of Fe2O3

CHEMISTRY IS ALL ABOUT PROPORTIONS :D

Answer:

I got it Right in Study Island

Explanation:

Answer:

A reaction that has the same number and type of atoms on each side of the equation

Explanation:

A pex

Answer:

Chemistry is the branch of science that deals with the properties, composition, and structure of elements and compounds, how they can change, and the energy that is released or absorbed when they change.

Answer:

Well my  teacher said a more complex way he said chemistry is the science that deals with the properties, composition, and structure of substances.

Explanation: