Which of the following is necessarily characterized by a covalent linkage?a. Base-pairing interactionb. Disulfide bondc. Hydrogen bondd. Induced fite. Van der Waals interaction

Answer:

1. Democritus - Matter was made of different kinds of things.

2. Bernoulli- Gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Substances combine or break apart to create new, different substances.

Explanation:

1. Democritus was a philosopher who because of his immense contribution to atomic theory was regarded as the "FATHER OF SCIENCE". His idea was that matter was made of different kinds of things called which he called ATOMOS meaning ATOM.

2. Daniel Bernoulli was another outstanding mathematician and scientist who played a major part in the kinetic molecular theory of gases via his "HYDRODYNAMICA". His idea, which states that "gases are formed from tiny particles so small you can’t see them. The particles are spread out into a certain area and move when people walk through them"

was based on fluid dynamics.

3. Joseph Priestley is remarkably known for his 1774 discovery of oxygen. His findings that air is a mixture of gases and not just a substance made of one element paved the way for his idea that " Substances combine or break apart to create new, different substances".

Explanation:

aam= 90%•20amu+10%•22amu/100

aam= 2020/100

aam= 20.2

Taking into account the definition of atomic mass, isotopes and atomic mass of an element, the average mass of the element is 20.2.

First of all, you have to know that atoms are made up of protons and neutrons in a central nucleus, as well as an electronic cloud (the extra-nuclear zone), a place where there is a greater probability of finding electrons orbiting the nucleus of the atom.

Then, it is neccesary to know that the atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus.

The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.

This is, isotopes are atoms whose atomic nuclei have the same number of protons but different numbers of neutrons.

Because the isotopes of an element have different atomic masses, the relative atomic mass or atomic weight is an average of the atomic masses of the different isotopes in a sample taking into account the relative abundance of each of them.

In this case, 90% of the isotopes have a mass number of 20 amu, while 10% have a mass number of 22 amu. Then, the average mass of the element can be calculated as:

20 amu×0.90 + 22 amu×0.10= 20.2

Finally, the average mass of the element is 20.2.

Learn more:

Answer:

protons and neutrons are found in nucleus

Answer:

Thickness = 5.0 * 10^-6 to 1 significant figure

Explanation:

Volume of oleic acid added:

2 drops when there are 100 drops per cm³ means that each drop has a volume of;

2 * 0.01 = 0.02 cm³

A 5% v/v oleic acid in solution will contain:

5/100 * 0.02 = 0.001 cm³ of oleic acid .

Area of circular film on the water surface = πr²

where r, radius = 16 /2 = 8cm, π = 3.14

Area = 3.14 * 8²

Area = 201 cm²

Since volume = area * height or thickness

Thickness = volume/area

Thickness = 0.001 cm³ / 201 cm²

Thickness = 0.00000498 or 4.98 * 10^-6 cm

Thickness = 5.0 * 10^-6 to 1 significant figure

Answer: SF6

Sulfur hexafluoride or sulphur hexafluoride, is an inorganic, colorless, odorless, non-flammable, non-toxic but extremely potent greenhouse gas, and an excellent electrical insulator. SF₆ has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom.

Answer:

Dipole-dipole interactions

Explanation:

Dipole-dipole interactions occur between two molecules with two polar end- a partially positive end and a partially negative end. The dipoles exists in these molecules due to the difference in the electronegativities of the atoms if the molecule. The positive end of a dipolar molecule will be attracted to the partially negative end of the neighboring molecule.

In the separation of molecules using silica gel as the adsorbent surface, the dominant interactive forces between the adsorbent and the materials to be separated are dipole-dipole interactions. The silica gel have polar SiOH groups on its surface which attracts polar molecules in the material to be separated. These polar molecules are strongly adsorbed to the silica gel surface whereas nonpolar or less polar molecules in the material to be separated are less strongly adsorbed, and thus, are eluted faster than the polar molecules.

Answer:

Earth's gravitational pull

Explanation:

Astronauts in the space shuttle float because they are in “free fall” around Earth, just like a satellite or the Moon. Again, it is gravity that provides the centripetal force that keeps them in circular motion.

Answer:

0.015 mol HCL

Explanation:

Molarity = moles solute/liters solution

Step 1: Define variables

M = 0.200

L = 75.0 mL

m = unknown, x

Step 2: Convert mL to L

1000 mL = 1 L

75.0 mL/1000 mL = 0.075 L

Step 3: Substitute

0.200 M = x mol/0.075 L

Step 4: Find x

x = 0.015 mol HCL

Answer:

Take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water.

Explanation:

Hello,

In this case, for the dilution process from concentrated  12-M hydrochloric acid to 1.00 L of the diluted 0.50M hydrochloric acid, the volume of concentrated HCl you must take is computed by considering that the moles remain constant for all dilution processes as shown below:

[tex]n_1=n_2[/tex]

Which can also be written in terms of concentrations and volumes:

[tex]M_1V_1=M_2V_2[/tex]

Thus, solving for the initial volume or aliquot that must be taken from the 12-M HCl, we obtain:

[tex]V_1=\frac{M_2V_2}{M_1} \\\\V_1=\frac{1.00L*0.5M}{12M}\\ \\V_1=0.0417L=41.7mL[/tex]

It means that you must take approx 41.7 mL of 12-M HCl in a 1.00-L flask and fill the rest of the volume with distilled water for such preparation.

Best regards.

Answer:

Explanation:

1) A fulcrum is a pivot point that plays a central role (not necessarily located at the center) in a lever. The fulcrum of the attached picture has been circled (in blue).

2) The object placed on this lever's measurement tray is balanced by placing it at the center of the tray. This is the standard way of placing objects on any balance.

The fixed point on the rigid bar around which the machine (lever) can turn is called the fulcrum. It refers to the support that the lever rotates around. For instance, the midway or support is where the rod will pivot in the case of a common balance.

1) A fulcrum is a pivot point that plays a crucial (but not always essential) role in a lever. The accompanying image's fulcrum has been highlighted in blue with a circle.

2) By putting it in the middle of the measurement tray for this lever, the object is balanced. The norm for placing items on any balance is in this manner.

The pivotal point of the beam is known as the fulcrum. A load is applied at the other end of a lever when an effort is exerted on one end of the lever.

The fulcrum can be shown as follows:

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Answer:

Red blood cells

Explanation:

An average adult human has somewhere around 25 trillion red blood cells in their body.

Answer:

Heya! Maddie here! The answer is Red Blood Cells.

Explanation:

Hope this helps!

Answer:

1. Democritus- Matter was made of

different kinds of things.

2. Bernoulli- Gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Substances combine or

break apart to create new different substances.

Explanation:

1. Democritus was a Greek philosopher regarded to be the "Father of Science". He discovered that all matter were composed of indestructible things he called ATOMOS. Hence, his idea was that Matter was made of different kinds of things (atoms).

2. David Bernoulli, a mathematician, was born in 1700. He contributed immensely to the kinetic molecular theory of gases. In his postulated theory, he gave the idea that gases are formed from tiny particles so small you can't see them. The particles are spread out into a certain area and move when people walk through them.

3. Priestley- Joseph Priestley, born in 1733, is widely known for his discovery of oxygen gas among other gases. His idea was that substances combine or

break apart to create new different substances.

Answer:

6.63

Explanation:

From the relationship;

pH = pKw/2

Pkw = 13.26

Then it follows that;

pH = 6.63

Hence if. pKw = 13.26, the pH = 6.63

Answer:

5 significant figures all figures are significant except for 0

Answer: Ionic compound are made by strong electrostatic interactions  in the middle of ion , which will result in higher melting points and electrical conductivity when being compared to covalent compounds . covalent counds have bonds where the electrons are shared allying atoms .

Hoped I Helped-

Sleepy~

Answer:

i believe it is 5

Explanation:

.......

Answer:

Slower

Explanation:

Different forces, such as gravity, can affect an object in many ways.

Scenario 1: A car is climbing a hill and then starts to coast.

Here, when the car starts to not accelerate anymore, gravity could pull it to slow down and eventually stop.

Scenario 2: A car is speeding downwards.

Here, when the car isn't on the gas pedal, gravity could act upon the car and make it go faster.

forces can make things move faster or slower them down.

Answer:

The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).

Explanation:

The reaction between an acid and a base is called neutralization, forming a salt and water.

Salt is an ionic compound made up of an anion (positively charged ion) from the base and a cation (negatively charged ion) from the acid.

When an acid is neutralized, the amount of base added must equal the amount of acid initially present. This base quantity is said to be the equivalent quantity. In other words, at the equivalence point the stoichiometry of the reaction is exactly fulfilled (there are no limiting or excess reagents), therefore the numbers of moles of both will be in stoichiometric relationship. So:

V acid *M acid = V base *M base

where V represents the volume of solution and M the molar concentration of said solution.

In this case:

Replacing:

0.0137 L* 0.129 M= V base* 0.135 M

Solving:

[tex]V base=\frac{0.0137 L*0.129 M}{0.135 M}[/tex]

V base=0.0131 L = 13.1 mL

The volume (mL) of 0.135 M NaOH that is required to neutralize 13.7 mL of 0.129 M HCl is 13.1 mL (option b).

Answer:

c- observations

hope this helps

Explanation:

Answer:

(b). Mass and distance.

Explanation:

The gravitational force between two objects is given by Newton's law of universal gravitation. The formula is as follows :

[tex]F=G\dfrac{m_1m_2}{r^2}[/tex]

Here,

G is universal gravitational constant

r is the distance between two objects

It is very clear that the gravitational force is directly proportional to the product of masses and inversely proportional to the square of the distance between them.

Hence, the two quantities are used to predict gravitational force according to Newton's law of universal gravitation are mass and distance.

Answer:mass and distance

Explanation:

it’s correct

Answer:

Explanation:

Chemistry is the science that studies the composition, structure and properties of matter and the changes it undergoes during chemical reactions and their relationship with energy

Explanation:

Chemistry is the branch of science concerned with the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances.

Answer:

1068.8 g of N₂ are required.

We can also say, 1.07 kg of N₂

Explanation:

Let's apply the Ideal Gas Law equation to solve the problem:

Formula is  P . V = n . R . T

At STP we know, that P is 1 atm and T is 273.15 K. So let's replace the formula:

1 atm . 855 L = n . 0.082 L.atm /mol.K . 273.15 K

(1atm . 855L) / (0.082 L.atm /mol.K . 273.15 K) = n

38.17 moles = n

Let's convert the moles to mass, nitrogen is a dyatomic gas → N₂

Molar mass N₂ = 28 g/mol

38.17 mol . 28 g/mol = 1068.8 g of N₂ are required.

AT STP the 1 moles of gas is equal to the 22.4 L of gas. The mass of the nitrogen gas in the 855 L tank at STP is 1068 g.

The mass of the Nitrogen gas can be calculate using the formula,

[tex]\bold {w = n \times m}\\[/tex]

Where,

w -mass = ?

n - number of moles = [tex]\bold {=\dfrac {855}{22.4} = 38.169\ moles }[/tex] at STP.

m - molar mass  [tex]\bold {N_2}[/tex] =  

Put the values in the formula,

[tex]\bold {w = 38.169 \times 28 = 1068.73\ g}[/tex]

Therefore, the mass of the nitrogen gas in the 855 L tank at STP is 1068 g.

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Answer:

The correct answer would be - observing with the help of five senses.

Explanation:

To find and describe the physical properties of the given substance or the solution or liquid students can observe using their five senses. By looking at the liquid one can find its state and color, by smelling students can find the odor of the sample, by touching it one can observe and describe the texture.

Fluidity can also be measure by the touch if the solution is viscous or free-floating. By using a thermometer and using a graduated cylinder one can find the temperature at room temperature and the weight of substance respectively.

Answer:

183 cg = 0.00183 kg

0.25 kg = 250 g

Explanation:

Use conversion factors. 1kg is equal to 1 x 10^5 cg (100000) and 1 kg is equal to 1 x 10^3 grams (1000 grams).

Answer:

Explanation:

move an object a greater distance than the distance that part of the machine was moved

Answer:

Explanation:

Answer:

Alkali Metals

Explanation:

Because they are in group one, but Hydrogen is not an alkali metal.

Answer:

[tex]\Delta \rho =2.22 g/mL[/tex]

Explanation:

Hello,

In this case, since a change in science is widely known to be considered as a subtraction between the the final and initial values of two measured variables and is represented via Δ, here the final density is 5.43 g/mL and the initial one was 3.21 g/mL, therefore, the change in density is:

[tex]\Delta \rho=\rho _f-\rho _i\\ \\\Delta \rho=5.43g/mL-3.21g/mL\\\\\Delta \rho =2.22 g/mL[/tex]

Best regards.

Answer:

18.91 ml

Explanation:

Initial volume of base=2.04 ml

Final volume of base = 20.95 ml

Volume of base used= 20.95 - 2.04 = 18.91 ml

Note that the volume of base used is obtained as the difference between the final and initial volume of base, hence the answer given above.

Answer:

15. Velocity = 3 X 10^8

     Distance = 1580 m

time = distance / velocity

t = 1580 / 3 * 10^8

t =  1580 * 10^-8 / 3

t = 158 * 10^-7/3

t = 5.26 * 10^-8 seconds  

16. Converting the distance to 'm'

Given distance (in miles), multiplying by 1.609 to convert to  km and also multiplying by 1000 to convert to 'm'

s= 4.8 * 1.609 * 10^7 * 1000

v = 3 * 10^8

t =  4.8 * 1609  * 10^7 / 3 * 10^8

t = 1.6 * 1609 * 10^-1

t = 2574.4 * 10^ -1

t = 2.5744 * 10^-4 s

17. Mass in 1 tsp of medicine = 5 mL at a density of 25 mg/mL

Mass in 1 tsp of medicine = 5 * 25 = 125 mg

Mass prescribed by the doctor  = 375 mg

Number of table spoons required = Mass prescribed / Mass in 1 tsp

N = 375/125 = 3 table spoons of the medicine

18. Density of medicine = 400g/ 5mL = 80g / mL

Medicine required = 1500 g

Volume of medicine required = Medicine Required / Density of medicine

Volume = 1500 / 80 = 18.75 mL of medicine is required

Hence, the volume of the suspension should be at least 18.75 mL

19. Volume of 10 drops = 1 mL

Volume of 5 drops = 1/2 mL

The faucet is leaking 5 drops or 1/2 mL water per minute

Number of minutes in a day = 60 * 24  = 1440 minutes in a day

Water leaked in 1440 minutes = 1440 * 1/2 = 720

0.720 L (720 mL) Water leaked from the faucet in a day

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Answer:

The creation of regulations that limit timber activities and the exploitation of wood can prevent soil erosion in Troy.

Explanation:

The exploitation of the wood was an intense activity and that did not have any regulation that would limit its damages, caused by its exploratory activities.

As the timber market was totally undisciplined, the exploitation of the wood caused a strong deforestation, leaving the soil totally unprotected and susceptible to strong erosion.

Soil erosion has a very negative impact on the environment, requiring regulations to be made to prevent this from happening.

Based on this, we can say that one way to prevent environmental problems in the seaport of troy is by establishing laws and regulations that limit logging activities.