Câu 15: Nguyên tử X nặng gấp 2 lần nguyên tử cacbon. Nguyên tử X đó có nguyên tử khối và

kí hiệu hóa học là

A. 24_Mg. B. 16_O C. 56_Fe D. 32_S

Answers

Answer 1

Answer:

A

Explanation:


Related Questions

You have an atom with 17 protons, 18 neutrons, a net charge -1, and a mass of 35. How many electrons does this atom have?

Answers

Answer:

this atom have 18 electrons

Explanation:

we know that in nutral state of atom , an atom have equal number of protons and electrons ,but in this question this atom is not nutral means it is charged this atom have -1 charge this means it gains 1 electron .in nutral state if an atom have equal number of proton and electron when the atom is charged(gain or lost certain amount of electron) number of electron become proton -the electron it losts or proton + the electron it gainsthis atom have -1 charge this means it gains 1 electron so the number of electron calculated by ; proton + the number of electron it gains; this atom have 17 protons so , number of electron =17+1=18there fore this atom have 18 electrons.

I think its helpful for you

According to the periodic table, which two elements have an atomic mass less than twice their atomic number?

Answers

Answer:

Hydrogen and oxygen

Explanation:

Hydrogen

2 × atomic number = 2

atomic mass = 1.008 amu

Oxygen

2 × atomic number = 16

atomic mass = 15.999 amu

A 3.90 L sealed vessel under vacuum is filled with 6.40 g of fluorine gas. What is the pressure (in kPa) of the vessel at 25.0 ⁰C ?

Answers

From the ideal gas law, the pressure of the gas is 106 kPa.

First we must obtain the number of moles of the gas;

Number of moles = mass/molar mass

Molar mass of fluorine gas = 38 g/mol

Number of moles of F2 = 6.40 g/38 g/mol = 0.168 moles

Using the ideal gas equation;

PV = nRT

P = ?

V = 3.90 L

n =  0.168 moles

T = 25.0 ⁰C + 273 = 296 K

R = 8.314  kPa L K-1 mol-1

Substituting values;

P = nRT/V

P =  0.168 moles × 8.314  kPa L K-1 mol-1 ×  296 K/3.90 L

P = 106 kPa

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The pressure of the vessel at a temperature of 25 °C is 106.73 KPa

We'll begin by calculating the number of mole of fluorine gas. This can be obtained as follow:

Mass of F₂ = 6.40 g

Molar mass of F₂ = 19 × 2 = 38 g/mol

Mole of F₂ =?

Mole = mass / molar mass

Mole of F₂ = 6.40 / 38

Mole of F₂ = 0.168 mole

Finally, we shall determine the pressure. This can be obtained as follow:

Volume (V) = 3.90 L

Temperature (T) =  25.0 °C = 25 + 273 = 298 K

Mole of F₂ (n) = 0.168 mole

Gas constant (R) = 8.314 L.KPa/Kmol

Pressure (P) =?

PV = nRT

P × 3.9 = 0.168 × 8.314 × 298

P × 3.9 = 416.232096

Divide both side by 3.90

P = 416.232096 / 3.90

P = 106.73 KPa

Therefore, the pressure of the vessel is 106.73 KPa

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Why is the periodic table not arranged by atomic weight and instead arranged by atomic number?

Answers

The chemical properties are mainly dependent on the electrons, or in some cases the charge of the protons, which is independent of the number of neutrons.So,they are arranged by increasing atomic number…
Atomic weight doesn't increase in a constant manner with respect to elements increase in atomic number.Where as while taking about atomic number it increases in a specific manner so it's easy to arrange a periodic table .

At before Duberinor,Mendeleev tried to use atomic weight but they failed .

please help n let me know thank u

Answers

I can’t see the question clearly can you type it

The temperature at which a solid melts is the same as the temperature at which its liquid form solidifies (true or false)​

Answers

Answer:

True I think so

Explanation:

I have asked question in my profile please tell me the answer

what is the resonance structure of ch3​

Answers

Answer:

For the CH3- structure use the periodic table to find the total number of valence electrons for the CH3- molecule. Once we know how many valence electrons there are in CH3- we can distribute them around the central atom with the goal of filling the outer shells of each atom.

In the Lewis structure of CH3- structure there are a total of 14 valence electrons.

Also note that you should put the CH3- Lewis structure in brackets with as 1- on the outside to show that it is an ion with a negative one charge.

----- Steps to Write Lewis Structure for compounds like CH3- -----

1. Find the total valence electrons for the CH3- molecule.

2. Put the least electronegative atom in the center. Note: Hydrogen (H) always goes outside.

3. Put two electrons between atoms to form a chemical bond.

4. Complete octets on outside atoms.

5. If central atom does not have an octet, move electrons from outer atoms to form double or triple bonds.

Lewis Structures, also called Electron Dot Structures, are important to learn because they help us understand how atoms and electrons are arranged in a molecule. This can help us determine the molecular geometry, how the molecule might react with other molecules, and some of the physical properties of the molecule (like boiling point and surface tension).

Explanation:

CH3CNO can be represented by at least three different but valid Lewis structures called resonance forms, or resonance structures, shown below.

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Answers

Answer:

The process in which plants release water through their leaves back into the air

Explanation

Answer:

The process in which plants release water through their leaves back into the air.

Hope this helps!

4. The cup is a volume widely used by cooks in the UAE. One cup is equivalent to 237 mL.
a. If 1 cup of olive oil has a mass of 216 g, what is the density of olive oil in kg/mL?


b. Convert the density from part A to kg/mL. Write your answer in scientific notation.

Answers

Taking into account the definition of density and scientific notation, the density of olive oil is 0.000911 [tex]\frac{kg}{mL}[/tex] or 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

Density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space.

In other words, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance.  That is, density is the relationship between the weight (mass) of a substance and the volume it occupies.

The expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:

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

In this case, you know that:

mass= 216 g= 0.216 kg (being 1000 g= 1 kg)volume= 237 mL

Replacing in the definition of density:

[tex]density=\frac{0.216 kg}{237 mL}[/tex]

Solving:

density= 0.000911 [tex]\frac{kg}{mL}[/tex]

On the other side, scientific notation is a quick way to represent a number using powers of base 10.  

The numbers are written as a product:

a×10ⁿ

where:

a is a real number greater than or equal to 1 and less than 10, to which a decimal point is added after the first digit if it is a non-integer number. n = a whole number, which is called an exponent or an order of magnitude. Represents the number of times the point decimal is shifted. It is always an integer, positive if it is shifted to the left, negative if it is shifted to the right.

In this case, the density expressed in scientific notation is: 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

In summary, the density of olive oil is 0.000911 [tex]\frac{kg}{mL}[/tex] or 9.11×10⁻⁴[tex]\frac{kg}{mL}[/tex]

Learn more

about density: brainly.com/question/952755?referrer=searchResults brainly.com/question/1462554?referrer=searchResultsscientific notation: brainly.com/question/18073768?referrer=searchResults

PLS I NEED HELP QUICKKKKK

Match each example to the type of wave.

B. Longitudinal wave
A. Transverse wave
C. Combination of longitudinal and transverse wave
D. Infrared wave
E. Radiant energy
F. Microwaves
G. Ultraviolet waves

Answers

Answer: These are all examples of the waves you listed

B- Soundwave, ultrasound waves

A-Surface ripples on water

C- water waves

D-The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared.

E-The heat emitted from a campfire.

F-Long Distance Wireless Transmission. Most wireless transmission systems are based on microwave technology.

G- Disinfectants

Explanation:

Hope this helps!!

Have a nice day!

3. Compare What is the
difference between a
chromosome and a
chromatid?
(Please answer in a simple sentence)

Answers

Answer:

A chromosome is a thread-like structure present in the nucleus  that is made up of a single molecule of DNA and proteins, carrying some or all genetic materials of an organism. A chromatid is an identical half of a duplicated chromosome

Explanation:

5. Calculate the mass percent of carbon in C3H8

Answers

Answer: How to calculate the mass percent by using these instructions

1.The molar mass is the mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol).

2.The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Explanation:

How do you prepare a demi-glace?

Answers

Answer:

Explanation:

sory i dont know

Demi-glace is a classic element of French cuisine. This dark brown sauce is made by reducing broth until it's thick and packed with flavor. It can be made from beef stock, chicken stock, or even vegetable stock. The traditional French version is made with veal.

Using the standardized NaOH solution in the previous
question, the titration of 5.00 mL of vinegar required
42.25 mL of NaOH. What is the % of acetic acid in the
vinegar? Previous standardized NaOH solution = 0.098

Answers

Answer: Using the standardized NaOH solution in the previous question, the titration of 5.00 mL of vinegar required 42.25 mL of NaOH. What is the % of acetic acid in the vinegar? Concentration of NaOH from previous question= 0.0986 M. David C.

Explanation:

Please mark as brainliest for me.Thank you so much

The percentage of acetic acid in vinegar is 4.988 %., When the titration of 5.00 mL of vinegar required 42.25 mL of NaOH.

What is titration?

Titration is defined as the process of chemical analysis method in which the amount of a sample's constituent is determined by mixing a precisely measured amount of the desired constituent with another material in a precise, known proportion. The equivalence point, or the point at which chemically equivalent amounts of the reactants have been combined, is to be detected by the titration.

According to the titration principle, V1=the volume of acetic acid and V1S1=V2S2

S1 is the acetic acid's strength

V1 = 42.25 ml * 0.0986 M / 5 ml = 0.833 M where V2 = Volume of NaOH S2 = Strength of NaOH

Hence, 1000 ml Vinegar contains 0.833 moles of acetic acid per 100 ml of vinegar (0.0833*60). G=4.998 grams of acetic acid

The amount of acetic acid in vinegar is 4.988%.

Thus, the percentage of acetic acid in vinegar is 4.988 %., When the titration of 5.00 mL of vinegar required 42.25 mL of NaOH.

To learn more about titration, refer to the link below:

https://brainly.com/question/2728613

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What Group is this atom located use a number only
*

Answers

7 count the dots in the middle for you answer and if not it’s 3

Is the molecule H2+ stable?

Answers

Answer: Yes

The antibonding orbital is empty. Thus, H2 is a stable molecule.

Answer: yes it is

Explanation:Bond order

The antibonding orbital is empty. Thus, H2 is a stable molecule

When doing medical research with human subjects, which four limitations are unavoidable?

Answers

Answer:

Answer

The limitations are-

1. Privacy of the individuals involved in the research process.

2. Physical and psychological risks should be minimized

3. The subjects should be chosen equitably

4. Only reasonable exposure to risks is admissible.

Explanation

The privacy of the individuals involved in the research must be taken into consideration. This will ensure safety of patient data and information. The risk of physical and physiological well being of the person must be taken into consideration in such a research. In addition to that, the subject must be made to understand every procedure and the risks involved before testing. Moreover, only minimal exposure to risks is allowed and must have been previously tested in animals to avoid deaths.

Please help me. I can’t give too much points bc I don’t have too much.

QUANTUM=
The relationship between energy and frequency=
E = hy
EN
h=
V=
Albert Einstein: PHOTONS

Answers

Answer is photons hope this helps

Calculate the number of days after the explosion for a sample of iodine-131 to go from 100%
iodine-131 to less than 1% iodine-131. Complete chart.

Answers

It will take 56 days to go from 100% iodine-131 to less than 1% iodine-131.

From the table, we can see that the half life of iodine-131 is 8 days. We can see that it takes 8 days to have 50% of iodine-131

After 16 days, we will have 25 % of iodine-131

After 24 days, we will have 12.5 % of iodine-131

After 32 days, we will have 6.25% of  iodine-131

After 40 days, we will have 3.125% of  iodine-131

After 48 days, we will have 1.5625% of iodine-131

After 56 days, we will have 0.78125% of iodine-131

After 56 days, the percentage of iodine-131 drops to less than 1%.

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1. What is the shape of an organic molecule containing a triple bond with respect to the carbons on either side of the bond?
Explain your answer

Answers

Answer:

The alkyne is linear

Explanation:

Any molecule with a triple bond is considered an alkyne. In regards to the shape, because carbon can only bond to 4 different atoms at once a triple bond fills in 3 of the required 4 atoms needed to reach the molecules ground state (when it's most stable). The more electrons shared between atoms, the shorter the bond will be which results in a stronger and more linear line. Keep in mind a quadruple bond is not possible between carbons as of now.

2.When copper (II) nitrate reacts with sodium hydroxide, copper (11) hydroxide is produced.
How many grams of copper (11) hydroxide can be prepared from 2.7 g of copper (II) nitrate
reacting with sodium hydroxide?

Answers

Answer:

 

2Cu + S ~~~> Cu2S Copper (C) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction.

Explanation:

Pure iron, Fe , can be produced from an ore called hematite, Fe2O3 , by reaction with carbon at high temperatures. 2Fe2O3+3C⟶4Fe+3CO2 How many tons of hematite must react with carbon if an iron company needs to make 49 tons of iron?

Answers

70 tons of hematite (Fe₂O₃) is needed to produce 49 tons of iron (Fe).

We'll begin by calculating the tons of hematite (Fe₂O₃) that reacted and the tons of Fe produced from the balanced equation. This is illustrated below:

2Fe₂O₃ + 3C —> 4Fe + 3CO₂

Molar mass of Fe₂O₃ = (56×2) + (16×3) = 160 g/mol

Mass of Fe₂O₃ from the balanced equation = 2 × 160 = 320 g

Divide by 907185 to express in ton

320 / 907185 = 0.000353 ton

Molar mass of Fe = 56 g/mol

Mass of Fe from the balanced equation = 56 × 4 = 224 g

Divide by 907185 to express in ton

224 / 907185 = 0.000247 ton

SUMMARY

From the balanced equation above,

0.000353 ton of Fe₂O₃ reacted to produce 0.000247 ton of Fe.

Finally, we shall determine the tons of hematite (Fe₂O₃) needed to produce 49 tons of Fe. This can be obtained as follow:

From the balanced equation above,

0.000353 ton of Fe₂O₃ reacted to produce 0.000247 ton of Fe.

Therefore,

X ton of Fe₂O₃ will react to produce 49 tons of Fe i.e

X ton of Fe₂O₃ = [tex]\frac{0.000353 * 49}{0.000247} \\\\[/tex]

X ton of Fe₂O₃ = 70 tons

Thus, 70 tons of hematite (Fe₂O₃) is needed to produce 49 tons of Fe.

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What happens to excess heat produced in the muscle during contraction and relaxation

Answers

Answer:

Calcium is then pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin.

Explanation:

Actin and myosin return to their unbound state causing the muscle to relax. Alternatively relaxation (failure) will also occur when ATP is no longer available.

When two atoms bond chemically it is because of the interaction between
A) the nuclei of each atom.
B) the protons in each atoms.
C) all electrons in the atoms.
D) the valence electrons in each atom.

Answers

Answer:

C

Explanation:

It depends on the bonding for an explanation.

If one atom is a metal and one is a non metal it will be ionic. This is because one atom transfers its electron to the other atom giving them both a charge. They will then be bonded due to opposite forces of attraction.

If both atoms are non metals it will be covalent. Electrons pair together in the center of two atoms that have merged together and they share their electrons.

(Makes more sense with diagrams)

which of the following is not true for chemical change

Answers

Answer:

"They can be reversed by physical changes."

Explanation:

A chemical change can form a new substance, can be detected by the change in color and they have properties different from their starting materials.

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Answers

Answer:

any form of water that falls from the sky

Which substances will make a salt when combined?

Vinegar and soda
Soda and wine
Detergent and ammonia
Fertilizer and vinegar

Answers

Answer:

vinegar and soda

Explanation:

Mixing baking soda (sodium bicarbonate) and vinegar (acetic acid) causes a chemical reaction that produces a salt (sodium acetate) and water, as well as carbon dioxide gas.

Answer:

Fertilizer and vinegar

Explanation:

Fertilizer is a base, and vinegar is an acid. Salt is made when you combine a base and an acid. Plus, I got a 100% on the test and this was my answer.

Which is not a type of nuclear decay?
A. Zeta
B. Gamma
C. Alpha
D. Beta

Answers

Answer:

The answer is Zeta

Explanation:

The three types of nuclear decay are Gamma, Beta, and Alpha.

PLEASE EXPLAIN I KNOW THE ANSWER I NEED AN EXPLAINATION

The potential energy as a function of internuclear distance for three diatomic molecules, X2, Y2, and Z2, is shown in the graph above. Based on the data in the graph, which of the following

Answers

From the graph shown, Y2 = N2, X2 = O2, Z2 = H2.

When atoms of elements are at a large distance from each other, the potential energy of the system is high. However, as the atoms approach each other, the potential energy of the system decreases steadily. The closer the atoms come to each other, the lower the potential energy. This implies that potential energy is proportional to bond length.

Since N2 has a shorter bond length and higher energy, Y2 must be N2. The bond energy of hydrogen is small hence H2 must be X2. The bond energy of a double bond is intermediate between that of a single and triple bond hence Z2 must be O2.

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what is the difference between exergonic and exothermic reactions?​

Answers

Answer:

An exergonic reaction is a type of chemical reaction that releases free energy to the surroundings. The final state of this reaction is less than its initial state. ... “Exothermic” literally means “outside heating” while “exergonic” literally means “outside work.”

Explanation:

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Have a happy day <3 Miss Hawaii

An exothermic reaction is where energy is given off as heat and an exergonic reaction is where energy is given off as light.
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