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

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.

Answer:

1)

Explanation:

ok this is a write answer

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:

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:

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:

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]

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Answer:

b and c since they bulge

Explanation:

Hey There :

Volume initial = ?

Volume final = 5000 mL

Molarity initial = 4 M

Molarity final = 0.1 M

Therefore :

Mi * Vi = Mf * Vf

4 * vi = 0.1 * 5000

4 vi = 500

Vi = 500 / 4

Vi = 125 mL

Answer A

Hope this helps!

Answer:

????

Explanation:

where's the question

Answer:

1-air

2-decrease

3-water

4-gas

5-liquid

I THINK the answer to part b is A but I am not entirely sure

Explanation:

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

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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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.

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.

Answer: yes it is

Explanation:Bond order

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

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!

Answer:

b.homogeneous

Can I have a Brainliest please?

Explanation:

Answer:

A. All isotopes have no charge

Answer:

c

a new substance is produced

The answer should be A

VisibleVisible wave length visible wavelength of light that are emitted by Adams can be used to get Nate explosive devices remotely

Explanation:

a brittle, High melting solid : option B (MgCl2).

1) H2S

2) H2O

3) I2

weakest to strongest.

hope this helps you.

Answer:

any form of water that falls from the sky

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

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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The concentration of 25 mL of potassium hydroxide can be determined from 0.1 M solution of hydrobromic acid by titration.

Titration involves the process by which the concentration of an unknown solution is determined by reaction a known volume of the unknown solution with a carefully measured volume of a standard solution. By determining the volume of the standard solution required to react completely with the solution of unknown concentration, its concentration can be accurately determined by calculation.

In order to determine the concentration of  25 mL of potassium hydroxide, this volume of solution is put into a conical flask and titrated against a known volume of 0.1 M solution of hydrobromic acid. At the end point, usually signified by a color change, the concentration of the 25 mL of potassium hydroxide solution can be calculated from the stoichiometry of the reaction.

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Answer:

1.chemical change 2, when two chemicals are mixed they have mix two chemcials into one liquid

Explanation:

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.

Answer:0.305g

Explanation:

mass = 79.9x(2.3 x 10^21) / (6.02 x 10^23)

= 0.305