During which step of this procedure does a chemical change occur?

A. 1

B. 2

C. 3

D. 4

Answer:

B. A mixture has different properties throughout; a pure substance has the same properties throughout

Explanation:

We have two classes of substances which are pure and impure substances.

Pure substances are elements and compounds

Impure substance are simply mixtures.

Mixtures have the following properties;

Answer:

[tex]n_{O_2}=3.84molO_2[/tex]

Explanation:

Hello!

In this case, since the combustion reaction of methanol is:

[tex]CH_3OH+\frac{3}{2} O_2\rightarrow CO_2+2H_2O[/tex]

In such a way, since there is 1:3/2 mole ratio between methanol and oxygen, we can compute the moles of oxygen that are needed to burn 2.56 moles of methanol as shown below:

[tex]n_{O_2}=2.56molCH_3OH*\frac{\frac{3}{2}molO_2}{1molCH_3OH} \\\\n_{O_2}=3.84molO_2[/tex]

Best regards!

Answer: Atomic radius decreases across a period and increases down a group.

Answer:

The number of moles of benzaldehyde = 0.0253 moles

Explanation:

The molecular formula of benzaldehyde is C₇H₆O

Its molecular mass is calculated from the atomic masses of the constituent atoms.

C = 12.0 g: H = 1.0 g; O = 16.0 g

Molecular mass = ( 12 * 7) + (1 * 6) + (16 * 1) = 106.0 g/mol

Number of moles of  substance = mass of substance/ molar mass of the substance

mass of benzaldehyde = 2.68; molar mass = 106.0 g/mol

Number of moles of benzaldehyde = 2.68 g/ 106 g/mol = 0.0253 moles

Therefore, the number of moles of benzaldehyde = 0.0253 moles

Answer:

3P2O5:

P:6 O:15

5CO2

C:5 O:10

3C6H12O6

C:18 H:36 O:18

4C6H12

C:24 H:48

3Mg3(PO4)2

Mg:9 P:2 O: 8

4(NH4)2S

N:8 H:32 S:4

Answer:Since dinosaurs are thought to be over 65 million years old, the news is stunning - and more than some could tolerate.  After the AOGS-AGU conference in Singapore, the abstract was removed from the conference website by two chairmen because they could not accept the findings.  Unwilling to challenge the data openly, they erased the report from public view without a word to the authors.  When the authors inquired, they received this letter:

Explanation:

i do not own my copyrights

Answer:

A.

Explanation:

A wave is a disturbance that moves energy from one place to another. Only energy — not matter — is transferred as a wave moves. The substance that a wave moves through is called the medium. That medium moves back and forth repeatedly, returning to its original position. But the wave travels along the medium

The volume at STP is 12.9L.

Possible symptoms include shortness of breath (difficulty breathing), a new or worsening cough, pain or tightness in the chest, hoarseness, or trouble swallowing. If you smoke and you know you've been exposed to high levels of radon, it's very important to quit smoking.

It comes from the natural decay of uranium which is determined in nearly all soils. It typically moves up via the floor to the air above and into your private home through cracks and other holes in the basis. your home traps radon inner, which it is able to build up.

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Answer:

Dude you need to provide an image because almost everyone is not gonna know what u talkin about.

Explanation:

Answer:

protons-positively charged

neutrons-uncharged

electrons- negatively charged

The differences are protons give out a positive charge neutrons are neutral and electrons give out negative charge.

Another one is the fact they are located on specific separate parts of an atom and each atoms consists a different amount each charge hope this helped :)

Explanation:

the object must be at rest

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\[/tex]

From the question we have

[tex]density = \frac{12.5}{1.35} \\ = 9.259259...[/tex]

We have the final answer as

Hope this helps you

Answer:

glucose and oxygen

Explanation:

Cellular respiration is the aerobic process by which living cells break down glucose molecules, release energy, and form molecules of ATP. Overall, this three-stage process involves glucose and oxygen reacting to form carbon dioxide and water.

Answer:

Of course, what we today call atoms can be divided into more elementary particles, but not that many.

Explanation:

Answer:

An electrical phenomenon is caused by flow of free electrons from one atom to another. The characteristics of current electricity are opposite to those of static electricity. Wires are made up of conductors such as copper or aluminum.

Explanation:

from google

Answer:Cellular respiration is not the same as breathing, but they are closely related

Explanation: When you breathe in, you take in the oxygen your cells need for cellular respiration. When you breathe out, you get rid of carbon dioxide that your cells produce during cellular respiration.

Answer: D. Potassium bromide

Answer:

C. Valence electrons

Explanation:

Please mark my answer as brainliest, I would appreciate it.

:)

What pH scale number represents a neutral.

The answer is 7

Answer:

The answer is 3 :)

Answer: 3. a bottle that was broken into many small pieces

Answer:

Barium and sulpher are the elements that forms barium sulphide .

And its molecular fomula is BaS.

Explanation:

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, in barium sulfide, barium and sulfur elements are present.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

An ionic compound is a metal and nonmetal combined compound.  Ionic compound are very hard. They have high melting and boiling point because of strong ion bond.  In barium sulfide, barium and sulfur elements are present. The molecular formula of the compound is BaS.

Therefore, in barium sulfide, barium and sulfur elements are present.

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Answer:

First is battery acid with a pH of 1, second is stomach acid with a pH of 1.5-3.5 (depends), third is antacid with a pH of 7, fourth is baking soda with a pH of 9, and finally, fifth is household ammonia with a pH of 11.

Here is a picture of the pH levels to better help you understand.

Answer:

b

Explanation:

Answer:

Well its B im sorry if im wrong.

Explanation:

The atomic weight of Aluminum (AL) is 26.98. It has 14 neutrons. Aluminum has  an atomic number 13. Therefore, option B is correct.

The atomic number of an element represents the number of protons in the nucleus of its atoms. Since the atomic number of an element is unique and determines its position in the periodic table, aluminum has an atomic number of 13.

The number of electrons in a neutral atom is equal to the number of protons, which in this case is 13. Therefore, aluminum has 13 electrons.

The atomic weight of aluminum (Al) is 26.98, which represents the weighted average mass of all the naturally occurring isotopes of aluminum, taking into account their relative abundances. The number of neutrons in an atom of aluminum is given as 14.

Thus, the correct option is B.

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Answer:

8

Explanation:

u can find it on ur chemistry book

Answer:

C. 8

Explanation:

Check chemistry textbook

Answer: Both of these are of great concern to human health. BPA is used in many things including plastic bottles and food packaging materials. Over time the polymer chains of BPA break down, and can enter the human body in many ways from drinking contaminated water to eating a fish that is exposed to the broken down toxins.

Explanation:

I think you will get it