What is the half-life of Technetium-99 if a 200 gram sample decays to 50 grams in 639,000 years?

Answer:

H

Explanation:

b/c the polyatomic PO4¯³

have 3 valance number

Answer:

Percent mass of oreo = 35.11%

Explanation:

Given:

Mass of oreo =  17.1

Mass of 1st cookie = 16.2

Mass of 3rd cookie = 15.4

Find:

Percent mass of oreo

Computation:

Total mass = Mass of oreo + Mass of 1st cookie + Mass of 3rd cookie

Total mass = 17.1 + 16.2 + 15.4

Total mass = 48.7

Percent mass of oreo = [Mass of oreo/Total mass]100

Percent mass of oreo = [17.1 / 48.7]100

Percent mass of oreo = 35.11%

Answer:

A!!!!!!!!

Explanation:

Answer:

Potential energy is stored energy. An object has a measurable amount of potential energy depending on where it’s located and how it relates to other objects around it — the energy of position.[1]  

An apple on the floor has very little potential energy. Lift it to the top of a skyscraper, and suddenly it has a lot of potential energy. It can fall to the ground under the force of gravity. It can also interact with other objects on its descent, such as striking a flying bird or landing on a car roof and damaging it.  

When the apple is descending, its potential energy has become kinetic energy, which is the energy of motion. Kinetic energy is the energy a person or an object has due to its motion — in this example, the falling apple. A parked bike on top of a hill has potential energy, which becomes kinetic energy once you start riding it downhill.  

Both of these energies are measured in joules. Energy is never destroyed or lost when changing from potential energy to kinetic energy — it is merely transformed from one energy type to another. This is known as the law of conservation of energy.[2]  

The potential energy of an object cannot be transferred to another entity – you cannot suck the potential energy out of the apple atop a skyscraper. Kinetic energy is transferable, as witnessed with the falling apple’s kinetic energy damaging a car or hitting a bird.  

What Is the Relationship Between Potential and Kinetic Energy?  

Relationship Potential and Kinetic Energy explained | Waterfall energy image

The relationship between potential energy and kinetic energy is that potential energy can transform into kinetic energy.  

Potential energy is position relative. In other words, it changes depending on an object’s height or distance and the mass of the object. Kinetic energy changes depending on an object’s speed and its mass.  

If we think about a waterfall, some still water at the top of the waterfall has potential energy. It isn’t moving and hasn’t gone over the edge. The water flowing from the waterfall has kinetic energy as it flows.[3]  

A pendulum is an excellent example of this relationship. As the pendulum swings ever higher upwards, its potential energy increases until it reaches its optimum at the highest point of the swing. At the top of the arc, the potential energy turns into kinetic energy as it swings back down.[4]  

What Are Examples of Potential Energy?  

There are two primary types of potential energy: gravitational potential energy and elastic potential energy.  

The gravitational force of the Earth causes gravitational potential energy. When a person jumps from a high dive board, they land with much force (and a splash) into the swimming pool below.  

The Earth’s gravity uses the diver’s gravitational force (their weight) to produce the kinetic energy (movement) that brings the diver into the pool. At the top of the diving board, we can talk about the diver’s gravitational potential energy.  

This is the same for apples on trees, bikes on top of a hill, a roller coaster waiting to descend, and a skydiver in a plane — all examples of the potential to do an amount of work.[5]  

Elastic potential energy occurs when you stretch or compress something. A rubber band left on a sideboard has little potential energy. If you pick it up and stretch it, you have increased its potential to do some work.  

If you release the rubber band, it may fly across the room or scare the cat. You manipulated the rubber band to increase its potential energy, which was then released as kinetic energy as it traveled (motion) across the room. An archer pulling back a bow and coiling a spring are further examples of potential energy.[6]  

Correct question is;

Resistance of a given wire is obtained by measuring the current flowing in it and the voltage difference applied across it. If the percentage errors in the measurement of the current and the voltage difference are 3% each, then error in the value of resistance of the wire is?

Answer:

6%

Explanation:

From ohms law, we know that;

R = V/I

Where;

R is resistance

V is voltage

I is current

Now, the percentage error in the resistance is given by the formula;

ΔR/R = ΔV/V+ ΔI/I

We are told that the current and the voltage difference have a percentage error of 3% each. Thus;

ΔR/R = 3% + 3% = 6%

Answer:

212 degrees

Explanation:

Answer:

212 degrees Fahrenheit

Explanation:

Similarly, if we heat a volume of water above 100 degrees Celsius, or 212 degrees Fahrenheit, water changes its phase into a gas called water vapor. Changes in the phase of matter are physical changes, not chemical changes.

Answer:

The abundance of 35/17 Cl is 75% and 25% of 37/17Cl

Explanation:

The molar mass of an atom is defined as the sum of the masses of each isotope times its abundance, that is:

35.5amu = 35amu*X + 37amu*Y (1)

Where X is the abundance of the 35/17Cl and Y the abundance of 37/17 Cl

As there are just these 2 isotopes and the abundances of both isotopes = 1:

X + Y = 1 (2)

Replacing (2) in (1):

35.5 = 35X + 37(1-X)

35.5 = 35X + 37 - 37X

-1.5 = -2X

X = 0.75 = 75%

And Y = 100-75% = 25%

Answer:

if I tell the ans u won't give me brainly

Answer:

I mean i dont know......

Explanation:

Answer:

SEE EXPLANATION

Explanation:

A)

1) The balanced  chemical reaction is;

Fe2O3 + 3H2O------> 2Fe(OH)3

2) C12H22O11------> 12 C + 11H2O

B)  1 is a combination reaction

     2 is a decomposition reaction

C) The molar mass of NH3 is 14 + 3(1) = 17 g/mol

Percentage composition of N = 14/17 * 100/1 = 82. 4 %

D) 1 mole of O2 contains 6.02 * 10^23 particles

E) For (NH4)3 PO4

We have 3(14 + 4(1)) + 31 + 4(16) = 149 g/mol

F) 1 mole of CaCO3 contains 100g of CaCO3

1.25 moles of CaCO3 contains 1.25 * 100/1 = 125 g of CaCO3

Answer:

salt i know the answer and even sugar is

Answer:

Solar energy is energy from the sun. for example solar panels are used to use energy for the sun to give you eletricity.

Explanation:

Explanation:

solar energy is energy from the sun, it can be used for electricity.

Answer:

Birds evolved from a group of meat-eating dinosaurs called theropods. That's the same group that Tyrannosaurus rex belonged to, although birds evolved from small theropods, not huge ones like T. rex.

Answer:

we haven't done anything to study the roots of the bird yet

Answer:

50.6g Al would be needed

Explanation:

Based on the reaction:

4Al + 3O₂ → 2Al₂O₃

4 moles of aluminium react with 3 moles of oxygen to produce 2 moles of Al₂O₃

To solve this question we need to find the moles of 45g of O₂. Then using the chemical equation find the moles of Al and its mass:

Moles O₂ -Molar mass: 32g/mol-:

45g O₂ * (1mol / 32g) = 1.41 moles O₂

Moles Al:

1.41 moles O₂ * (4mol Al / 3mol O₂) = 1.875 moles Al

Mass Al -Molar mass: 26.98g/mol-:

1.875 moles Al * (26.98g / mol) =

50.6g Al would be needed

The amount of aluminum that would be required to completely react with 45 grams of O2 would be 50.59 grams.

From the balanced equation of the reaction:

[tex]4 Al + 3 O_2 ---> 2 Al_2O_3[/tex]

The mole ratio of Al to O2 is 4:3.

Mole of 45 grams of O2 = mass/molar mass

                                     = 45/32

                                           = 1.4063 moles

Equivalent mole of Al: 4 x 1.4063/3

                                    = 1.875 moles

mass of Al = mole x molar mass

                 = 1.875 x 26.98

                  = 50.59 grams

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A chemical property of a substance is a certain characteristic that can only be observed by participating in a chemical reaction. Alternatively, a chemical property of a substance is something that can only be observed when the substance undergoes a chemical change.

I'm not sure what you're supposed to do with the first four boxes; all four are examples of chemical properties. Do you have to name the specific type of chemical property as given in the description? If so, the following would be my answers:

Flammability/Combustibility: The ability of a substance to burn.

The next two are quite strange; I'm not aware of a term that cleanly describes reactivity with water or acid. I suspect that, given the level of the material here, the general property of "reactivity" might be the answer for both the second and third descriptions

(Water-)reactivity: Some substances react when put in water.

(Acid-)reactivity: Some substances react when put in acid.

Light sensitivity: Light can interact with some things to form new substances.

As for the chart, I've filled it in as shown in the attached image. Please take care to double-check what I've written; in particular, when it comes to the property, I might have used a different term from what you were taught in class or provided in some other resource that I don't have access to. I've also color-coded qualitative/quantitative and physical/chemical for your convenience.

Answer:

5SiO2 + 2CaC2 ➡ 5Si + 2CaO + 4CO2

Explanation:

This question involves balancing the above equation. An equation is said to be BALANCED when all the atoms of each element in the reactant side equates that in the product side.

According to this question, a chemical reaction is given as follows: SiO2 + CaC2 = Si + CaO + CO2. Based on observation, the atoms of elements are Silicon, oxygen, calcium and carbon are not the same on the reactants and products side. Based on this, the balanced equation is:

5SiO2 + 2CaC2 ➡ 5Si + 2CaO + 4CO2

Answer:

The numerical value for the acceleration of gravity is most accurately known as 9.8 m/s/s.

Answer:

it would be 4.5 mole left over

Explanation:

The greatest amount of MgO will be 7.8 mole and Mg will be limiting reagent.

The substance that would be entirely absorbed in the end of the chemical process is called as the limiting reagent.

A mole would be defined as the quantity of a material that includes precisely 6.02214076 X [tex]10^{23}[/tex] of the particular chemical elementary entities.

Calculation of amount of  MgO

The balanced chemical equation is 2 Mg + [tex]O_{2}[/tex] → 2MgO

It can be seen that 2 mole of Mg reacts with 1 mole of oxygen.

So, 7.8 mole of Mg = 7.8 / 2 = 3.9 mole of [tex]O_{2}[/tex].

Since, [tex]O_{2}[/tex] will be added in given reaction vessel will be 4.7 moles.

So, (4.7 - 3.9) = 0.8 moles of [tex]O_{2}[/tex] left but in this case Mg will be finished. Therefore, Mg will be limiting reagent.

It can be understood that 2 moles of Mg will give 2 mole of MgO.

That's why , 7.8 moles of Mg = 2 × 7.8 / 2 = 7.8 moles of MgO.

Therefore, 7.8 mole of magnesium oxide (MgO) could be generated and Mg will be limiting reagent.

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Answer:

B

Explanation:

IM A CHEMISTRY WIZZZZ

:)

I hope u get full marks on your paper/test/quiz or whatever!

There is a 20 percent chance so stay positive!

Answer:

D

Explanation: ultraviolet rays are harmful to humans

Answer:

A. Florine has a stronger pull than Magnesium

Explanation:

Electronegativity refers to the tendency in which an tom would attract electrons to itself.

Below each element in the periodic table is their electronegativity value. Florine has the highest electronegativity value of 4.0.

Going through options;

A. Florine has a stronger pull than Magnesium

Florine = 4.0

Magnesium = 1.2

This correct

B. Hydrogen has a stronger pull than Phosphorus

Hydrogen = 2.1

Phosphorus = 2.1

This is wrong

C. Potassium has a stronger pull than Sodium

Potassium = 0.8

Sodium = 0.9

This is wrong

D. Iron has a stronger pull than Bromine

Iron = 1.8

Bromine = 2.8

This is wrong

Answer:

C. a positive calcium ion and a negative oxygen ion

Explanation:

Ionic bonds are generally positive and negative because one is gaining electrons while the other is losing.

The term chemical bond generally refers to the attractive force that holds the constituent atoms or ions of a molecular species together. Here an ionic bond is formed between a positive calcium ion and a negative oxygen ion. The correct option is C.

An ionic compound is formed by the transfer of one or more electrons between the atoms. An ionic bond or electrovalent bond refers to the strong electrostatic forces of attraction that hold together oppositely charged ions.

The number of electrons lost or gained by an atom of an element so as to acquire a stable octet configuration in its outermost shell is called the electrovalency of the element.

Here 'Ca' has 20 valence electrons and 'O' has 6 valence electrons. So in order to attain the stable octet configuration of 'Ar', 'Ca' loses two electrons whereas 'O' accepts two electrons to attain stable octet configuration of 'Ne'.

Thus the correct option is C.

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Answer:

Oh Okay

I hope u have a better rest of ur day

Answer:

A. Eggs and sperm

Explanation:

Genres are an organisms reproductive cells. Also referred to as sex cells. Females they are ova or egg cells, and males they are sperm.

Answer:

Second-degree burns, or partial thickness burns, are more severe than first-degree burns. They affect the outer layer of skin, called the epidermis, and part of the second layer of skin, called the dermis. Second-degree burns can be very painful and often take several weeks to heal.

Explanation:

Answer:

A. Empirical formula => C₂H₄O

B. Molecular formula => C₄H₈O₂

Explanation:

From the question given above, the following data were obtained:

Mass of C = 0.273 g

Mass of H = 0.046 g

Mass of O = 0.182 g

Molar mass of compound = 88 g/mol

A. Determination of the empirical formula of the compound.

C = 0.273 g

H = 0.046 g

O = 0.182 g

Divide by their molar mass

C = 0.273 /12 = 0.023

H = 0.046 /1 = 0.046

O = 0.182 /16 = 0.011

Divide by the smallest

C = 0.023 / 0.011 = 2

H = 0.046 / 0.011 = 4

O = 0.011 / 0.011 = 1

Thus, the empirical formula of the compound is C₂H₄O

B. Determination of the molecular formula of the compound.

Empirical formula = C₂H₄O

Molar mass of compound = 88 g/mol

Molecular formula =?

Molecular formula = [C₂H₄O]ₙ

[C₂H₄O]ₙ = 88

[(12×2) + (4×1) + 16]n = 88

[24 + 4 + 16]n = 88

44n = 88

Divide both side by 44

n = 88 / 44

n = 2

Molecular formula = [C₂H₄O]ₙ

Molecular formula = [C₂H₄O]₂

Molecular formula = C₄H₈O₂

Explanation:

A covalent bond can be thought of as a 'shared pair' of electrons, so there are 2 electrons in each bond. That means that a double bond will have 4 electrons in the space between the bonded nuclei, and a triple bond will have 6.

Answer:

v = 16 m/s

Explanation:

Given that,

Distance, d = 400 m

Time taken, t = 25 s

We need to find the speed of the horse. Speed is equal to distance covered divided by time taken. So,

[tex]v=\dfrac{d}{t}\\\\v=\dfrac{400\ m}{25\ s}\\\\v=16\ m/s[/tex]

So, the speed of the horse is 16 m/s.