giving brainliest please help!

Answer:

A communicable disease

Explanation:

Diseases that can be transferred are known as communicable diseases.

Answer:

Chemical that can be mixed with another chemical to reduce the dangerous of a specific chemichal

the amount of energy absorbed when 240 dm3 of hydrogen, measured at room temperature and pressure, is formed.

According to Avogadro's law 1 mole of any gas occupies 22.4 L (dm3) at room temperature and pressure.

So the amount of energy absorbed:

(kJ)E=131∗240/22.4

=1403.6(kJ)

1403.6 kJ is absorbed when 240 dm3 of hydrogen, measured at room temperature and pressure is formed.

Answer:

the dendritic cell consumes the pathogen by phagocytosis

Explanation:

Haloalkanes and other compounds with the halogen atom bonded to either sp3-hybridized or sp2-hybridized carbon atoms (aryl and vinyl halides) react with magnesium metal to yield organomagnesium halides called Grignard reagents. Grignard reagents are usually prepared in diethyl ether (CH3CH2O─CH2CH3). An ether solvent is essential for the reaction. The French chemist Victor Grignard discovered this reaction in 1900, and it has been studied and used extensively ever since.

Grignard reagents form easily from 1°, 2°, and 3° alkyl halides, although their reactivities differ. Aryl and vinyl halides react somewhat more slowly, and the cyclic ether tetrahydrofuran (THF) is required to prepare Grignard reagents of these compounds. The higher boiling point of the cyclic ether provides more vigorous reaction conditions, but the rate of the reaction also increases because THF solvates the Grignard reagent better than diethyl ether.

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Molecular model of a complex of methyl-magnesium chloride, a Grignard reagent, in which two molecules of tetrahydrofuran, THF, are bound to magnesium. The model is based on the crystal structure.

The order of reactivity of the halogens in haloalkanes is I > Br > CI > > F. Organofluorides are so unreactive that they are never used to prepare Grignard reagents. Organohalogen compounds containing bromine and chlorine are readily available, and are commonly used to prepare Grignard reagents. Grignard reagents are used synthetically to form new carbon–carbon bonds. A Grignard reagent has a very polar carbon–magnesium bond in which the carbon atom has a partial negative charge and the metal a partial positive charge.

The polarity of the carbon–magnesium bond is opposite that of the carbon–halogen bond of haloalkanes. Because the carbon atom in a Grignard reagent has a partial negative charge, it resembles a carbanion, and it reacts with electrophilic centers such as the carbonyl carbon atom of aldehydes, ketones, and esters. We will discuss this chemistry extensively in later chapters.

Grignard reagents react rapidly with acidic hydrogen atoms in molecules such as alcohols and water. When a Grignard reagent reacts with water, a proton replaces the halogen, and the product is an alkane. The Grignard reagent therefore provides a pathway for converting a haloalkane to an alkane in two steps.

The gas given off at the cathode is hydrogen while the gas given off at the anode is oxygen.

The term electrolysis has to do with the decomposition of a substance by the passage of direct current through it.

The ions present in the system are H^+, OH^- and NO3^- ions. The gas given off at the cathode is hydrogen while the gas given off at the anode is oxygen.

The half reaction equation of the reduction is;

2H^+(aq) + e ----->H2(g)

The oxidation half reaction equation is;

4OH^- (aq)------> 2H2O(l) + 4e

The overall equation is;

4H^+(aq) + 4OH^- (aq)------> 4H2(g) + 2H2O(l) + 4e

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Answer:

To keep apparatus, chemicals and carry out experiments

Using the stoichiometry of the reaction and the information provided in the question, the mass of N2 used is 11.62 g.

The term chemical reaction refers to the combiantion of two or substances to yiled one or more products. The reaction equation in this case is N2 + O2 --->2NO.

Now;

Number of moles of NO = 25g/30 g/mol = 0.83 moles

1 mole of N2 yields 2 moles of NO

x moles of N2 yileds 0.83 moles of NO

x = 0.415 moles

Mass of N2 = 0.415 moles * 28 g/mol = 11.62 g

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Answer:

9.69g

Explanation:

Xmol of n2= 7.774/22.4= 0.346 mole

molar mass of n2 2×14 =28g/Mol

Mas of n2= 0.346×28

Mas of n2=9.69grams

Answer 2. Accept with minor revisions: Also known as conditional acceptance, this decision means that the paper requires minor changes for it to be ...

wer:

Explanation:

Answer:

Explanation:

As the distance to the outermost electron of the Group 1 element increases, the amount of energy required to remove an electron decreases.

That's D

A: and C: are both incorrect for the same reason. Group 1 elements don't add electrons -- they try and give those electrons away.

B: all of the group one have only 1 valence electron,

Answer:

the correct answer false

Explanation:

Answer:

B. A gnat completes its life cycle in about 1 month.

Explanation:

Stage Time in Stage

egg 24 hours

larva 7 days

pupa 6 days

adult 2 weeks

Which of the following is a valid conclusion that Ivana can draw from her data?

A. Agnat generally does not live for more than 1 week.

B. Agnat completes its life cycle in about 1 month.

C. Agnat life cycle has more than five stages.

D. Agnat is a crustacean, not an insect.

Answer:

The correct answer is Na2CO3. 10H2O

Answer:

We should manage and conserve forest resources in Nepal.

Explanation:

Nepal is the second richest country in natural resources. We should all work together and conserve our natural resources. We can conserve and manage forests in Nepal by the following ways:

1. Proper rules and laws should be made as well as executed by our government.

2. Illegal activities regarding harm of forests and its resources should be totally band.

3. Awareness programmes should be conducted worldwide to aware our citizens regarding conservation of forests.

Answer:

"The Roman numeral denotes the charge and the oxidation state of the transition metal ion. For example, iron can form two common ions, Fe2+ and Fe3+. To distinguish the difference, Fe2+ would be named iron (II) and Fe3+ would be named iron (III)."

Explanation:

In chemistry, Roman numerals are used for a specific group of elements called transition metals. The Roman numerals indicate the charges that these metals carry in a compound.

Answer:

False

Explanation:

While we do know that A. Leeuwenhoek used a simple microscope that consisted of only 1 lens, Hooke used a compound microscope. Although, after trying a compound microscope, Hooke found out that it strained his eyes and continued to use a simple microscope for his Micrographia.

Thus, we can say that the (compound) microscopes used today are different than the (simple) microscope used by Hooke and Leeuwenhoek.

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Here's the balanced chemical equation for above reaction ~

[tex]\qquad \sf  \:LiBr + F \rightarrow Li F + Br[/tex]

Here, fluorine is more more more reactive than Bromine, therefore it replaces Bromine from its compound and forms Lithium floride.

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The Correct choice is : D

if temperature is held constant, then they have same average kinetic Energy because there's no change in energy caused by transfer of heat or something.

According to the forces of attraction, if temperature is constant the particles have the same average kinetic energy.

Forces of attraction is defined as  a force by  means of which atoms in a molecule  combine. it is basically an attractive force in nature.  It can act between an ion  and an atom as well.It varies for different states  of matter that is solids, liquids and gases.

The forces of attraction are maximum in solids as  the molecules present in solid are tightly held while it is minimum in  case of gases  as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.

The physical properties such as  the melting point, boiling point, density  are all dependent on forces of attraction which exists in the substances.

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The initial temperature of the copper piece if a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C is 345.5°C

The initial temperature of the copper metal can be calculated using the following formula on calorimetry:

Q = mc∆T

mc∆T (water) = - mc∆T (metal)

Where;

According to this question, a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C. If the final temperature of water is 42.0 °C, the initial temperature of the copper is as follows:

400 × 4.18 × (42°C - 24°C) = 240 × 0.39 × (T - 24°C)

30,096 = 93.6T - 2246.4

93.6T = 32342.4

T = 345.5°C

Therefore, the initial temperature of the copper piece if a 240.0 gram piece of copper is dropped into 400.0 grams of water at 24.0 °C is 345.5°C.

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Answer:

the correct answer is 364

q = m * c * ΔT

where q is the heat absorbed or released, m is the mass of the substance, c is the specific heat capacity of the substance, and ΔT is the change in temperature.

We can assume that the heat lost by the copper is gained by the water, so:

q(copper) = -q(water)

where the negative sign indicates that the copper loses heat while the water gains heat.

The specific heat capacity of copper is 0.39 J/g °C, so:

q(copper) = 240.0 g * 0.39 J/g °C * (T(copper) - 24.0 °C)

The specific heat capacity of water is 4.18 J/g °C, so:

q(water) = 400.0 g * 4.18 J/g °C * (42.0 °C - T(copper))

Setting q(copper) equal to -q(water), we get:

240.0 g * 0.39 J/g °C * (T(copper) - 24.0 °C) = -400.0 g * 4.18 J/g °C * (T(copper) - 42.0 °C)

Simplifying and solving for T(copper), we get:

T(copper) = [(400.0 g * 4.18 J/g °C * 42.0 °C) + (240.0 g * 0.39 J/g °C * 24.0 °C)] / (240.0 g * 0.39 J/g °C + 400.0 g * 4.18 J/g °C)

T(copper) = 364.1 °C

Therefore, the initial temperature of the copper piece was 364.1 °C.

Hence, the answer is "364 °C".

Answer:

10.25

Explanation:

There I proved it

Answer:

pOH = 12.10

Explanation:

pOH = 14 - pH = 14 - 1.90 = 12.10

Answer:

Its False

Explanation:

Its False because the concentartion would have to be the solute the thing being added. BUT if you add the equal amount of solvent and add more solute than the one you added more solute is the more concentarted.

AN EXAMPLE:

An example we have Cup A and Cup B we add the same amount of water to both cups but i add more solute to cup A (Examples of solute Salt,powder)  and i add less solute to b I balance them in a balance. and cup A is the most concentrated because It has more solute.

ANOTHER EXAMPLE:

Lets do the same thing i add the same amount of water to cup A and B I want to add the same solute but i cant since Cup A saturates At 8 Spoons And B at 6 So  cup A is most concentared

Conclusion:

So it all depends on the solute how much you add or at how many spoons you saturate.

Thats all I hope it helped!!

The concentration of the solution depends upon the number of moles of solute with changing, the concentration will change. Therefore, the given statement is false.

The concentration of the given solution can be determined in the terms of molarity, Normality, and molality. We can easily calculate the molar concentration of a substance in a solution.

In chemistry, concentration can be described as the abundance of a constituent divided by the total volume of a mixture. The concentration can be mass concentration, number concentration, molar concentration, and volume concentration.

The concentration of the solution determined as the number of moles of a solute per unit volume of a solution is known as molarity or molar concentration.

The Molar concentration of a solution is evaluated in the following way.

Molarity (M) of the solution = Moles of solute/Volume of the Solution

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Answer:

Ok so To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity).  The pH is then calculated using the expression:

pH = - log [H3O+].

Example:  Find the pH of a 0.0025 M HCl solution.  The HCl is a strong acid and is 100% ionized in water.  The hydronium ion concentration is 0.0025 M.  Thus:

pH  =  - log (0.0025) = - ( - 2.60) = 2.60

Explanation:

The hydronium ion concentration can be found from the pH by the reverse of the mathematical operation employed to find the pH.

[H3O+] = 10-pH  or  [H3O+] = antilog (- pH)

Example:  What is the hydronium ion concentration in a solution that has a pH of 8.34?

8.34 = - log [H3O+]

- 8.34 = log [H3O+]

[H3O+] = 10-8.34 = 4.57 x 10-9 M

On a calculator, calculate 10-8.34, or "inverse" log ( - 8.34).

Answer:

2 significant figures

Good luck with your work! :)

n this questions certain

a

r

e

g

i

v

e

n

,

of moles ,n = 21 mol, Pressure P = 78 atm, Temperature T = 900 K, Volume V = ?

We have to calculate the volume of the given moles of gas at specific temperature and pressure.

Using Ideal Gas equation;

PV = nRT

V = nRT /P ( R = gas constant = 0.08206 L atm

m

o

l

−

1

K

−

1

)

V= 21 mol x 0.08206 L atm

m

o

l

−

1

K

−

1

x 900K / 78 atm

V= 73.854 L atm / 78 atm = 0.946 L

Answer:

 A chemical reaction can release chemical energy stored in batteries, natural gas, and even coal. The main advantage of chemical energy is that it is abundant in nature. Chemical energy can be produced by many organic materials.

Hope this helps!!!!!!

Mark Brainleast!!!!!!!!!!!!

a. the mole of substance

b.a standard solution

in analytical chemistry standard solution is a solution containing a precisely known concentration of an element or a substance.

A known mass of solute is dissolved to make a specific volume. it is prepared using a standard solution,such as a primary standard.

hope this helps you

Best describes the forces in the nucleus of a stable atom is the strong nuclear force balances out the electrostatic force.

The center region of an atom, which is composed of two different types of particles, is known as the atomic nucleus. Protons with positive charges and neutrons with no charges are present. Because of the strong electrostatic attraction between positively charged protons, atomic nuclei should be unstable, however they occasionally remain stable for more than a billion years.

The stability of nuclei suggests that protons and neutrons are attracted to one another by an attractive force. The strong nuclear force, also known as the residual strong force, is responsible for every individual atomic nucleus' stability. Neutrons and protons are held together by this basic force of nature. It is used to explain the atom's and its nucleus' stability, which is otherwise puzzling. It can be used to explain the origin of all atoms and, consequently, the origin of all known simple and complex molecules.

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Answer:

It's C.

Explanation:

According to the site, "http://needtoknow.nas.edu/energy/energy-sources/renewable-sources/wind/" ... "Wind energy is an indirect form of solar energy created by a combination of factors, including the uneven heating of Earth’s atmosphere by solar radiation, variations in topography, and the rotation of Earth. People have been putting wind energy to use throughout history to propel sail boats, mill flour from grain, and pump water."