The cutoff frequency for a certain element is 1.22 x 1015 Hz. What is its work function in eV?
Hint: 1 eV 1.60 x 10-19 J
=[?] eV

someone please teach me how to solve this its gonna make me cry

Answer:

C

Explanation:

a, b and d   are physical properties ..... the compound or element in question has not changed its identity

   c    when combined with oxygen, it has changed to a different compound via CHEMICAL property.

The correct answer to this question is option A.

Answer:

8.3 g of NaCl

Explanation:

Edge 2022

Answer:

8.3 g NaCl

Explanation:

Its right just type it in

Heating up a reaction increases the speed of a reaction until the enzyme denatures.

Enzyme denaturation occurs when a biological protein catalyst does not work anymore due to a high temperature that alters its tridimensional conformation.

This cellular process (denaturation) is well known to be one of the main causes of enzymatic failure.

In conclusion, heating up a reaction increases the speed of a reaction until the enzyme denatures.

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The type of scientist would most likely study how the size of the lemming population affects the size of the snowy owl population is a biologist.Thus, the correct option is (D)

Biologists study humans, plants, animals, and the environments in which they live.

They may conduct their studies--human medical research, plant research, animal research, environmental system research--at the cellular level or the ecosystem level or anywhere in between.

Hence, The type of scientist would most likely study how the size of the lemming population affects the size of the snowy owl population is a biologist.Thus, the correct option is (D)

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To test for hydrogen, burn a candle near the suspected source of hydrogen. If you hear a squeaky pop sound, hydrogen is present because when hydrogen gas burns, it makes a squeaky pop sound.

Hydrogen burns with a loud pop in when a burning splint is held near it.

There are a couple of ways to test for hydrogen. However, the simplest and most popular way is to bring a burning splint near a container containing hydrogen gas.

The production of a loud squeaky pop sound indicates the presence of hydrogen gas. All precautions should, however, be observed.

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Answer:

b) Product

c) Combustion

c) speeds up the rate of reaction

Explanation:

the substance produced by a chemical reaction is called a product (b)

Combustion (c) reactions are involving oxygen and "another substance" [and hydrocarbons] to produce carbon dioxide and water.

A catalyst acts to speed up the rate of a reaction (c)

 > note how it "speeds up" reaction: , it [a catalyst] lowers the pressure or temperature needed to start one--but it isn't used/consumed in the reaction

So, the answers are: b, c, c

hope this helps!!

Answer:

2.17 gm Al

Explanation:

First, find the number of moles .   Then multiply by the mole weight of aluminum.

# moles =   4.85 x 10^22 / 6.022 x 10^23 = .08053 moles

.0805 moles * 26.981 gm/mole  = 2.173 gm

Answer:

Sample A=40 Sample B=50

Explanation:

32+48=80

32/80x100=40

The 100 is to convert it to a percentage

___________________________

Sample B

same thing

30+30=60

30/60x100=50

The mass percent of sulfur in compound B is 50 %

Mass percent is defined as a way of expressing a concentration or describing the component in a particular mixture.

It can also be defined as a mass of a element or solute divided by the mass of compound or solvent.  

Mass percent of sulfur of sample A

= 32 + 48 = 80

= 32 / 80 x 100

= 40 %

Mass percent of sulfur of sample B

= 30 + 30 = 60

= 30 / 60 X 100

= 50 %

Thus, the mass percent of sulfur in compound B is 50 %

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Answer:

B. the reaction absorbs energy (+ or endothermiic)

Answer:

n

Explanation:

nobody knows

Answer: O

Explanation:

Out of the given elements, oxygen has the highest electronegativity.

Answer:

Explanation:

Solution

Verified by Toppr

2 molL

−1

Explanation :

Concentration =

Volume of solution

Moles of solute

We assume that potassium nitrate dissolves in the given volume of solvent without gross change in volume.

Concentration =

101.10gmol

−1

404g

Answer:

Ionic bonding happens when an atom of an element gives one or more of its electrons to the other element's atom..it usually takes place between metal and non metal atoms...like in NaCl, Na gives its valence electron to chlorine and completes its own octet. Chlorine accepts the electron and completes its own octet too...but now both the atoms have an opposing charge and hence they attract each other to form an IONIC bond.

Ionic bonds are the strongest of the bonds...here complete transfer of electrons takes place unlike covalent bonds.

HOPE IT HELPED..

:)

Answer:

The electrostatic interaction between an anion and cation

Monosaccharides are the group of carbohydrates that are the simplest form of sugar. Option A galactose is a monosaccharide sugar.

Monosaccharides are simple sugars and are the fundamental unit of carbohydrates.

The general structural formula for the monosaccharides is (CH₂O)ₙ

The structure of the monosaccharide sugar contains carbon, oxygen, and hydrogen molecules in their structure.

Galactose that is a simple sugar with six carbon atom rings Hence,  option A is a correct option

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24 molecules of H2O are needed by the plant to produce 4 molecules of sugar.

The process by which plants convert carbon dioxide, water, and sunlight into oxygen and sugar-based energy is known as photosynthesis.

                   6CO2 + 6H2O + Sunlight → C6H12O6 + 6O2

The following three significant activities are involved in photosynthesis:

1. Chlorophyll absorbs light energy.

2. Water molecules are divided into hydrogen and oxygen and light energy is converted to chemical energy.

3. Carbon dioxide is converted to sugars.

Therefore, a plant needs four molecules of H2O and four molecules of CO2 to make one molecule of glucose or sugar, hence a plant needs 24 molecules of H2O and 24 molecules of CO2 to make four molecules of sugar.

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Answer:

D) 24 molecules of H2O

Explanation:

Just did the test on Edge 2023 and got it right. Have a nice day :)

Carbon monoxide blocks oxygen in the blood. Hence, option A is correct.

Combustion is a chemical process or a reaction between Fuel (Hydrocarbon) and Oxygen.

During incomplete combustion part of the carbon is not completely oxidized producing carbon monoxide (CO). Incomplete combustion uses fuel inefficiently and carbon monoxide is released.

Carbon monoxide gas diffuses rapidly across the pulmonary capillary membrane, binding to haemoglobin with an affinity 200 times that of oxygen to form carboxyhemoglobin. By displacing oxygen, CO decreases the oxygen-carrying capacity and oxygen delivery to tissues, causing marked cellular hypoxia and acidosis.

Hence, option A is correct.

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The volume of the tin piece in cubic centimetres is 4.3 cm³

A graduated cylinder is a standard piece of laboratory glassware used to measure the volume of an object or amount of liquid. As its name indicates, it is a glass cylinder with marks along the side similar to those on a measuring cup.

When adding an object to a liquid, the displayed volume difference corresponds to the volume of the added object.

In this way, to find the value of the object's volume, subtract the initial volume from the final volume:

16.8ml - 12.5ml = 4.3ml

To convert to cubic centimetres, the conversion scale of volume and length measurements need to be used, finding that mL is equal to cubic centimetres. So, the final answer is:

4.3 cm³

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Hydropower can affect fish and other marine life which is the true statement and is denoted as option C.

This is the process in which water energy is converted into electrical energy through the use of dams and turbines.

When the dams are created, it blocks the path of marine activities and limits them to certain activities such as reproduction.

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Answer:

15 grams of water will absorb 2,500 Joules  in going from 20.0 to 60.0 C.

Explanation:

The heat involved in raising a mass (m) of a substance with a specific heat (c) from one temperature to another (Delta T) is given by:

Heat = mc(Delta T)

2,500 Joules = m*(4.186J/gC)*(60C-20C)

2,500 Joules = m*(4.186J/gC)*(40C)

2,500 Joules = m*(4.186J/gC)*(40C)

m = (2,500J)/(4.186*40J/g)

m = 14.93 grams

Answer: B (15g)

Explanation:

The most abundant isotope among the given Isotopes will be Isotope B

To calculate the percent abundance of each isotope in a sample of an element, we usually divide the number of atoms of a particular isotope by the total number of atoms of all isotopes of that element and then multiply the result by 100.

% Abundance =  15/50 x 100

                        =  30 %

% Abundance =  30/50 x 100

                        =  60 %

% Abundance =  5/50 x 100

                        =  10 %

Hence, The most abundant isotope among the given Isotopes will be Isotope B.

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All liquids evaporate if exposed to certain elements.

Evaporation is the process by which water changes from a liquid to a gas or vapor.

Evaporation is the primary pathway that water moves from the liquid state back into the water cycle as atmospheric water vapor.

All liquids evaporate if exposed to certain elements.

The rate at which a liquid evaporates depends on its molecular structure.

The other factors that affect evaporation are surface area, temperature and air movement.

We can also do a few fairly simple experiments to demonstrate the effect that the various factors have on the rate of evaporation.

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The quantum numbers are used to describe the position of an electron in atom.

The quantum numbers are used to describe the position of an electron in atom. I have attached a picture that shows the complete question.

For the 1s orbital;

n =1

l = 0

ml = 0

ms = ±1/2

For the 2s orbital;

n = 2

l = 1

ml = -1, 0, 1

ms = ±1/2

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Answer:

1.1713 moles

Explanation:

RFM of N2O5= (14*2)+(16*4)=108

Moles of N2O5= Mass/RFM= 63.25/108= 0.5856 moles

Mole ratio of N2O5:NO2 = 2:4

Therefore moles of NO2= 4/2*0.5856= 1.1713 moles

The earth's mantle will not change in the future because this region is safe from the intervention of human beings.

The transfer of heat and material in the mantle helps us to determine the landscape of Earth. Activity in the mantle moves the plate tectonics, that contributes to volcanoes, seafloor spreading, earthquakes, and building of mountains.

So we can conclude that the earth's mantle will not change in the future because this region is safe from the intervention of human beings.

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Answer:

Ni atoms are contained in 1.25gram is 1.28e22 atoms.

Explanation:

Ni atoms are contained in 1.25gram is 1.28e22 atoms.

We have a Nickel(Ni)  atom . The atomic number of Ni is 28 .It is a silvery-white metal with a slight golden tinge. Ni belongs to the transitional metal series.

The electronic configuration of Ni = Ar4d⁸35²

Nickel is slowly oxidized by air at room temperature.

Nickel is a ferromagnetic element at approximately room temperature.

To answer the problem , we first need to divide by the molar mass of Ni to get the moles of Ni. And then we will multiply by Avogadro's number to find the number of Ni atoms.

Molar mass of Ni = 58.7gm

Given mass of Ni = 1.25gm

Avogadro’s No. = 6.022 × 10²³ atom/mole

                    Moles of Ni = Given mass/Molecular mass

                                          = 1.25/58.7 = 0.0213

                    Moles of Ni = 0.0213

Now ,

       Number of Ni atom = Avogadro’s number × Moles

So that,

                No. of Ni atom = 6.022 × 10²³× 0.0213

                                            = 0.128 ×10²³  atoms

                                           = 1.28 × 10²² atoms

                                           = 1.28e22

So there are 1.28 × 10²² individual Ni atoms are contained in 1.25 grams of Ni.

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Answer:

A.

Explanation:

Well, Nicola Tesla was from Croatia.

Albert Einstein was from Germany.

Thomas Edison was from the U.S.

So I think all over.

Answer: 2.5

Explanation: you devide mol solute which is 2.0 and the L solution which is 0.80M, and after you divide the two you get 2.5

i also had this question <3

The molarity is an important method to calculate the concentration of a solution. The volume of potassium nitrate of 0.80 molarity and 2.0 mol moles is  2.5 L.

The molarity of a solution is defined as the number of moles of the solute present per litre of the solution. It is mainly employed in calculating the molarity of a binary solution. It is represented as 'M' and unit is mol L⁻¹.

The equation used to calculate the molarity is given as:

Molarity = Number of moles of the solute / Volume of the solution in litres

Here molarity = 0.80 M

Number of moles = 2.0 mol

Then the volume of the solution =  Number of moles of the solute / Molarity

Volume = 2.0 / 0.80 = 2.5 L

Thus the volume of the solution is 2.5 L.

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The molarity of the unknown solution will be 1.310 M.It is denoted by M₂.

Molarity is defined as the ratio of the moles to the volume of the solution.

Given data;

Volume of unknown solution,V₁ = 10.5 mL

The volume of diluted solution,V₂ = 80.0 mL

Molarity of new solution,M₁ = 0.172 M

Molarity of unknown solution, M₂=?

For dilution we use the formula as;

M₁V₁=M₂V₂

M₂=M₂V₂/V₁

M₂ = ( 80 × 0.172 ) / 10.5

M₂= 1.310 M

Hence the molarity of the unknown solution will be 1.310 M.

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The change in enthalpy for the reaction per mole is -130KJ/mol.

Given,

Reaction: MgO(s) + 2HCl (aq) →MgCl₂ (aq) + H₂O (l)

1.32 g MgO is combined with 100.0 mL of 1.00 M HCl in the cup of coffee.

Change in temperature, ΔT=34.4 °C-24.2 °C =10.2°C

Specific heat of the HCl solution, c= 4.18 J/g·°C

Density= 1.00 g/mL

Mass can be written as the product of density and volume.

Mass= Density × Volume= 1g/ml × 100 ml=100g

Heat can be written as

Heat, Q=mcΔT=100g×4.18 J/g·°C×10.2°C=4263.6J

Number of moles of the MgO,

n= (mass of MgO)/(Molar mass)= 1.32g/(40.3g/mol)= 0.03275 mol

Change in Enthalpy, ΔH=-Q/(n)=(-4263.6J)/(0.03275 mol)

ΔH= -1300186J/mol= -130KJ/mol

Hence, the change in enthalpy for the reaction per mole is -130KJ/mol.

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