what is the president for 2020

Answer:

273.9m/s

Explanation:

Given parameter:

Kinetic energy of the ball  = 4.5kJ

Mass of the ball  = 120g

Unknown:

Speed of the ball  = ?

Solution:

Kinetic energy of a body is the energy due to the motion of a body.

 K.E  = [tex]\frac{1}{2}[/tex] m v²

where m is the mass

           v is the speed

Convert the quantities to the appropriate units;

     4.5kJ to J  = 4.5 x 10³J

 120g to kg  = 0.12kg

Now insert the parameters and find the unknown:

       4500  = [tex]\frac{1}{2}[/tex] x 0.12 x V²  

      9000 = 0.12V²  

       V²  = [tex]\frac{9000}{0.12}[/tex]   = 75000

        V  = 273.9m/s

Answer:

ABC

Explanation:

hrdjyt

Answer:

Hydrogen peroxide is a highly reactive chemical containing the elements hydrogen and oxygen. Pure hydrogen peroxide is a colourless liquid, but it is sold on the market as solutions in water, containing up to 33 – 37% pure hydrogen peroxide and other additives to stop the product decomposing.

Explanation:

Hope this helps <3

Answer:

6,500 gm of steam require= 3,510 kilo calories (approx)

Explanation:

Every 1 gram of water at 100° C  absorb 540 calories

So,

Total water = 6.5 kg = 6,500 gram

So,

6,500 gm of steam require = 6,500 x 540

6,500 gm of steam require= 3,510 kilo calories (approx)

According to the question,

Total water,

Temperature,

Now,

Required steam will be:

= [tex]6500\times 540[/tex]

= [tex]3510 \ kilo \ calories[/tex]

Thus the above answer is right.

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Answer:

C₂H₂(g) + 2.5 O₂(g) ⇒ 2 CO₂(g) + H₂O(l)   ΔH° = -1300 kJ/mol

Explanation:

In the combustion of acetylene, it reacts with oxygen to produce carbon dioxide and water. The corresponding chemical equation is:

C₂H₂(g) + 2.5 O₂(g) ⇒ 2 CO₂(g) + H₂O(l)

The thermochemical equation includes the balanced chemical equation, stating the states of aggregation and the enthalpy of the reaction.

C₂H₂(g) + 2.5 O₂(g) ⇒ 2 CO₂(g) + H₂O(l)   ΔH° = -1300 kJ/mol

Answer:

wait

Explanation:

a. The pH of this solution is 9.45.

b. If 0.88 g of NaOH is added to the solution, the pH will be  9.74.

a way to gauge how basic or acidic a material or solution is. On a scale of 0 to 14, pH is measured. A pH of 7 indicates neutrality on this scale, which implies it is neither acidic nor basic. More basic substances have a pH value more than 7, whereas more acidic substances have a pH value less than 7.

first of all we should calculate the molarity of the compounds

no. of moles of NH₃ = weight / molecular weight = 1.68 / (14+3) = 0.099

no. of moles of (NH₄)2SO4 = 4.05 / {2×(14+4) + 32 + 64} = 0.031

no. of moles of NH4+ = 2×0.031 = 0.062

[NH₃] = no. of moles / volume(L) = 0.099/ 0.5 = 0.198

[(NH₄⁺] = 0.031/0.5 = 0.124

1) now we know that

pH + pOH = pkw

pOH = pkw - pH = 14 - pH ---- -1

also

pOH = pkb + log ( [salt]/[base])

from 1

14 - pH = pkb + log ( [salt]/[base])

putting values

14- pH = -log(1.8e-5) + log(0.124/0.198)

14 - pH = 4.54

pH = 9.45

2) if 0.88g NaOH is added then as we know that NaOH is a base then it will reduce the buffer capacity

as there would be OH- ions initially present

hence the buffer action will move backward

i.e

pOH = pkb + log {(salt-x) / (base+x)}

where x= molarity of NaOH

no of moles of NaOH = 0.88 / (23+16+1) = 0.022

molarity of NaOH = 0.022/0.5 = 0.044

then 14 - pH = -log(1.8e-5) + log{ (0.124-0.044) / (0.198+0.044) }

14 - pH = 4.26

pH = 9.74

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Answer:

D. AgN.

Explanation:

Hello!

In this case, since the boiling point of a solution increases are more solute remains dissolved in the liquid, as more energy is required to start the phase transition, for insoluble solids for which we know the solubility product which has the following relationship with the amount of ions in solution:

"the greater Ksp, the more ions the solution has"

In such a way, for the solid with the greatest Ksp we understand it has most of the ions in solution and therefore the highest boiling point, thus, among the choices, D. AgN is the one with the highest boiling point because it Ksp is 7.2E-11, whcih is the greatest.

Best regards!

Explanation:

All period have the same number of shells

Answer:

cells are a basic unit of structure and function all things

Answer:

B

Explanation:

i just read it na, but i forgot the explanation

Answer:

A. and B.

Explanation:

Anion is negative as well as a negative ion.

(Just took the quiz)

Answer:

This question appears incomplete

Explanation:

There is no such element known as "Ballardium (Bu)" in the periodic table. However, there are elements with a bit of similarity in spellings and pronunciation such as Beryllium (Be) which is found in group 2 (meaning it is an alkali earth metal), Berkelium (Bk) which is an actinide (meaning it is radioactive) and Vanadium (V) which is found in group 5 of the periodic table (meaning it's a transition metal).

Answer: 0.048 cubic meters

Explanation:

Volume of a rectangular solid is lxwxh.  So you multiply the given dimensions.

Answer:

3.43×10¹ mol

Explanation:

Given data:

Initial number of  moles = 12.4 mol

Initial volume = 122.8 L

Final volume = 339.2 L

Final number of moles = ?

Solution:

The number of moles and volume are directly proportional to each other at same temperature and pressure.

Formula:

V₁/n₁  =  V₂/n₂

Now we will put the values,

122.8 L/ 12.4 mol  =  339.2 L / n₂

n₂ = 339.2 L× 12.4 mol  / 122.8 L

n₂ = 4206.08 L.mol /122.8 L

n₂ = 34.3mol

In scientific notation:

3.43×10¹ mol

The sentence that has an accurate punctuation is found in (Option B).

The punctuation marks are those marks that are use to make a piece of writing to have a complete meaning. A piece of writing will be meaningless if there are no attached punctuation marks.

The sentence that is correctly punctuated is;  "I bought all the ingredients for dinner: eggs, tomatoes, macaroni, and cheese—and told Molly to preheat the oven."(Option B)

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Answer: A

Explanation:

Metalloids

Answer:

[tex]k=8.63x10^{-8}\frac{1}{M*s}[/tex]

Explanation:

Hello!

In this case, since the differential rate law of a second-order reaction is:

[tex]\frac{dC_A}{dt}=-kC_A^2[/tex]

Whereas A stands for NOCl and the corresponding integrated rate law is:

[tex]\frac{1}{C_A} =kt+\frac{1}{C_A_0}[/tex]

Thus, since we know the concentrations and the elapsed time, we compute the rate constant as shown below:

[tex]k=( \frac{1}{C_A}-\frac{1}{C_A_0} )/t\\\\k=( \frac{1}{0.83M}-\frac{1}{0.878M} )/763,200s\\\\k=8.63x10^{-8}\frac{1}{M*s}[/tex]

Best regards!

Answer:

if it ain't changing direction the acceleration isn't being affected

Answer:

The main function of the immune system is to provide immunity to the body. Immunity is the body's ability to protect itself from the pathogens it is exposed to. Immunity depends on the body's ability to differentiate between things that belong in the body and those that do not. The immune system's first line of defense includes physical and chemical barriers that are always ready and prepared to defend the body from infection.

The skin acts as a barrier against pathogens. Some structures of the first line of defense include the skin, mouth, eyes, ears, nose, and stomach. The skin produces sweat and oil that work together to keep pathogens from the entering the body. Saliva and tears contain substances the can destroy pathogens. The ears and the stomach help fight pathogens.The ears produce ear wax that prevent pathogens from entering the ears. The stomach produces a liquid the kills pathogens.

Mucus is produce by the nose, lungs, throat, and stomach. Mucus traps pathogens. Mucus also prevent pathogens from getting into deep tissues. Anyway, the very first line of defense against any invasion of the human body is a set of physical barriers between the inside of the body and the outer world.

*my notes from edge2020*

Hope this helps ^-^

Answer:

0.52g of Al(OH)₃

Explanation:

The reaction of aluminium nitrate, Al(NO₃)₃, reacts with KOH, as follows:

Al(NO₃)₃ + 3KOH → Al(OH)₃ + 3 KNO₃

That means 1 mole of aluminium nitrate reacts with 3 moles of potassium hydroxide.

To find moles of aluminium hydroxide we need to determine the limiting reactant finding moles of each reactant:

Moles aluminium nitrate:

0.050L * (0.20mol / L) = 0.01 moles Al(NO₃)₃

Moles KOH:

0.200L * (0.100mol / L) = 0.02 moles of KOH

Thus, for a complete reaction of 0.02 moles of KOH are needed (Using the chemical equation)

0.02 moles of KOH * (1 mol Al(NO₃)₃ / 3 mol KOH) = 0.0067 moles of Al(NO₃)₃.

As there are 0.01 moles of Al(NO₃)₃, this is the excess reactant and KOH is the limiting reactant.

The 0.02 moles of KOH produce:

0.02 moles of KOH * (1 mol Al(OH)₃ / 3 mol KOH) = 0.0067 moles of Al(OH)₃

In mass (Using molar mass of Al(OH)₃: 78g/mol):

0.0067 moles of Al(OH)₃ * (78g/mol) =

Answer:

Explanation:

The stereochemical structures of the two compounds of the fumarase-catalyzed reaction are in the attachment below. The reaction been referred to is illustrated in the equation below

HOOCCH=CHCOOH + H₂O ==> HOOCCH₂CH(OH)COOH

The compounds attached are trans-2-butenedioate (which is one of the reactants) and (s)-2-hydroxysuccinate (which is the product formed)

Note that stereoisomers are isomers that differ in spatial orientation, thus there are other isomers that could contain the same atoms and have slightly but different spatial orientation such as cis-2-butenedioate and (r)-2-hydroxysuccinate

How do the products of chemical reactions compare to their reactants?

Answer:

The products often have completely different properties than the reactants.

The correct answer to the question is: The products often have completely different properties than the reactants.

In a chemical reaction, the reactants and products of the reaction have different properties because during the reaction, bonds were broken and new bonds were formed which generate a new substance called the product.

However, chemical equations must be balanced in order to conform to the law of conservation of matter which states that matter can neither be created nor destroyed  during a chemical reaction but can be transferred from one form to the other.    

For example, the reaction of Hydrogen gas (H₂) and oxygen gas (O₂) to produce water (H₂O)

From the equation, we can see that the reactants are gases but the product is a liquid which has a different properties from the gaseous reactants.

Therefore, the correct answer to the question is:  The products often have completely different properties than the reactants.

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Answer:

1. 4.93 = pKb of the weak base

2. pH = 12.61

Explanation:

1. When a weak base, B, is being titrated with HCl, the reaction occurs as follows:

B + HCl → BH⁺ + Cl⁻

That means the moles added of HCl are the moles of BH⁺ produced and moles of B are initial moles of B - Moles of HCl

Thus:

Moles B:

Initial moles:

0.0250L * (0.130mol / L) = 3.25x10⁻³ moles B

Moles HCl:

8.5x10⁻³L * (0.130mol / L) = 1.105x10⁻³ moles HCl

3.25x10⁻³ - 1.105x10⁻³ =

Moles BH⁺ = Moles HCl:

pH of the buffer made from B/BH⁺ is determined using H-H equation for weak bases:

pOH = pKb + log [BH⁺] / [B]

Where pOH is 14-pH = 14-9.36 = 4.64

pKb is pKb of the weak base, our unknown.

[BH⁺] could be taken as moles of BH⁺ =  1.105x10⁻³ moles

And [B] as moles of B = 2.145x10⁻³ moles B

Replacing:

pOH = pKb + log [BH⁺] / [B]

4.64 = pKb + log [1.105x10⁻³ moles] / [2.145x10⁻³ moles]

4.64 = pKb -0.288

2. When HCl and NaOH are in solution the reaction that occurs is:

HCl + NaOH → H₂O + NaCl

To find pH we need to determine, first, which reactant is in excess:

Moles HCl:

0.023L * (0.230mol / L) = 5.29x10⁻³ moles

Moles NaOH:

0.033L * (0.0230mol / L) = 7.59x10⁻³ moles

That means NaOH is in excess and after the reaction will remain:

7.59x10⁻³ moles - 5.29x10⁻³moles = 2.3x10⁻³ moles NaOH = Moles of OH⁻

In 23+33mL = 56mL = 0.056L:

2.3x10⁻³ moles OH⁻ / 0.056L = 0.0411M [OH-]

As pOH = -log [OH-]

pOH = 1.39

pH = 14 - pOH

Answer:

???

Explanation:

not really sure lol

Answer:

its B

Explanation:

Because its can only go cold to hot. -hope this help :)

Answer:

• All groups (columns) have the same number of valence electrons

Explanation:

Every group or column have the same number of valence electrons as a suprise. Every column is aligned in this way.

Answer:

all members within any group

Explanation:

Answer: .063

Explanation:

1.53g Mg * (1 mol Mg/ 24.3 g Mg) * (1 mol H2/1 mol Mg) = .063 mol H2

The mole of hydrogen gas that will be produced from the reaction would be 0.0630 moles.

From the equation of the reaction:

[tex]Mg(s) + 2 HCl(aq) ---> MgCl_2(aq) + H_2(g)[/tex]

The mole ratio of Mg to H2 gas is 1:1. Thus, for every one mole of Mg consumed by the reaction, 1 mole of H2 is produced, all other things being equal.

Recall that: mole = mass/molar mass

1.53 g of magnesium = 1.53/24.3

                                     = 0.0630 mole (to 3 significant figures)

Since the mole ratio of Mg to H2 is 1:1, it means that the number of moles of hydrogen gas produced would also be 0.0630 moles.

More on calculating moles can be found here: https://brainly.com/question/21085277

Answer:

[tex]E=9.62\times 10^{-21}\ J[/tex]

Explanation:

Given that,

The wavelength of a microwave is 7.42 mm or 0.00742 m

No. of photons, n = 359

We need to find the energy produced by this no of photons. It can be given by the formula as follows :

[tex]E=\dfrac{nhc}{\lambda}\\\\E=\dfrac{359\times 6.63\times 10^{-34}\times 3\times 10^8}{0.00742}\\\\=9.62\times 10^{-21}\ J[/tex]

or

[tex]E=9.62e^{-21}\ J[/tex]

So, the required energy is [tex]9.62\times 10^{-21}\ J[/tex].

Answer:

⬆️That guy deserves brainliest

Explanation:

Answer:

Sedimentary rock, rock formed at or near Earth's surface by the accumulation and lithification of sediment by the precipitation from solution at normal surface temperatures

Explanation: