PLEASE HELP! THIS A TIMED QUIZ!!
Scientists found an artifact that has 25% of Carbon-14 left. Based on how much Carbon-14 is remaining, how old is the artifact that was found?

A). 17,100 years
B). 5,700 years
C). 22,800 years
D). 11,400 years

90 grams. When the state of an object changes, the mass doesn’t change.

*edited*

Answer:

Since the gastropod is not unique, it cannot be an index fossil. An index fossil must be found over a wide area of the Earth. Since the gastropod is widely spread, it cannot be an index fossil.

Explanation:

Answer:

Topping the list of concerns is hydrogen burns. In the presence of an oxidizer -- oxygen is a good one -- hydrogen can catch fire, sometimes explosively, and it burns more easily than gasoline does.

Answer:

hydrogen burns

hope it helps

Answer:

C. It Will Provide information to help formulate a new hypothesis in the future.

Explanation:

I had AP Chemistry.

The following statement that it will provide information to help formulate a new hypothesis in the future is  true about a hypothesis that is proven to be inaccurate.

Hypothesis can be defined as an assumption which is made for the sake of argument . It is an interpretation of a practical condition for which action needs to be taken.It is defined as a tentative assumption which is made to test logical consequences.It is an antecedent clause of a statement which is conditional.

It is constructed before research. There are six types of hypothesis 1)simple hypothesis 2) complex hypothesis 3) directional hypothesis 4)non-directional hypothesis 5) null hypothesis 6)casual hypothesis

The hypothesis should be clear and precise, it must be specific and way of explanation of hypothesis should be simple.

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Answer:

7.6125

Explanation:

multiply 7.5 with 1015

yll got 76125 divide it by 1000 to get answer in grams

The mass in grams of 7.5 × 10¹⁵ molecules of ammonia is 21.08 × 10⁻⁸ g.

Mass of any substance from moles will be calculatd as:

n = W/M , where

W = required mass

M = molar mass

We know that in 1 mole of any substance 6.022 × 10²³ particles of that sybstance are present.

No. of moles in 7.5 × 10¹⁵ = 7.5 × 10¹⁵molecules / 6.022 × 10²³ molecules per mole

No. of moles in 7.5 × 10¹⁵ = 1.24 × 10⁻⁸ moles

Molar mass of ammonia = 17 g/mol

Now we put the requred values on the first equation to get the mass as:

W = (1.24 × 10⁻⁸mol)(17 g/mol)

W = 21.08 × 10⁻⁸ g

Hence required mass of ammonia is 21.08 × 10⁻⁸ g.

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Answer:

wavelength

Explanation:

Answer:

answer on what no file attached

Explanation:

Answer:

Igneous rocks form when magma (molten rock) cools and crystallizes, either at volcanoes on the surface of the Earth or while the melted rock is still inside the crust. All magma develops underground, in the lower crust or upper mantle, because of the intense heat there. first question Natural non-living things: They are found in nature and are not made by man. Examples: Sun, moon, stars, sky, clouds, rocks, mountains and many more. Man-made non-living things: They are made by man. Examples: Toys, chairs, tables, beds, houses, buildings, trains and many more. second question Metamorphic rocks form from heat and pressure changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock. The word "metamorphic" comes from Greek and means "To Change Form". third question. Sedimentary. fourth question and sorry I can't answer the last :(

Explanation:

Answer:

Kinetic energy

Explanation:

Answer

involving electrical charges: electrical

involving energy stored in chemical

bonds: thermal

involving the position and motion of

an object: mechanical

involving the motion of atoms: chemical

Explanation:

almost 100 this is right, sorry if this is wrong :)

Answer:Evaporation

Explanation:

The suns heat speeds the movement of water molecules, until the molecules move fast enough that they jolt out the surface of the water individually. Overtime the water gradually evaporates into water vapor.

Answer:

car is in the driveway

water is flowing in the river

a man is. walking in the road

a bird is flying in the sky

a tiger is running in the jungle

a tiger is running to eat a breakfast

Answer:

mabey c or d

Explanation:

color, odor, density, melting temperature, boiling temperature, and solubility are examples of physical properties. Physical properties can be used to identify a pure substance.

Answer:

Mass = 154.67 g

Explanation:

Given data:

Mass of aluminum chloride produced = ?

Mass of chlorine = 123.2 g

Solution:

Chemical equation:

2Al + 3Cl₂  →   2AlCl₃

Number of moles of chlorine:

Number of moles = mass/molar mass

Number of moles = 123.2 g/ 71 g/mol

Number of moles =1.74 mol

Now we will compare the moles of aluminum chloride and chlorine.

                          Cl₂              :              AlCl₃

                            3               :                 2

                           1.74            :          2/3×1.74 = 1.16 mol

Mass of AlCl₃:

Mass = number of moles × molar mass

Mass =  1.16 mol × 133.34 g/mol

Mass = 154.67 g

The given element nitrogen have 7 electrons and 7 protons. Mass number is the sum of number of protons and neutron. The number of neutrons is 7. Thus mass number of the isotope is  14.

Nitrogen is 7th element in periodic table. It is an electronegative element and is included in p block. Nitrogen exists as gas but sometime it can be liquified under high pressure.

Isotopes are atoms with same atomic number and different mass number. Nitrogen have two isotopes. N-14 and N-15. Mass number is the sum of number of protons and neutrons.

Even though isotopes are different in mass number their chemical properties will be similar but there exists slight changes in their physical properties.

Here, we have 7 protons and 7 electrons therefore, the mass number 14.Thus the isotope given in the diagram is N-14.

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Answer:

Because they have complete electronic configuration

Explanation:

Group 18 elements are known as the noble or inert gases. The elements in this group are non-reactive because they have complete electronic shell configuration.

Answer:

Its positive charge is attracted to the negative charge of Cl-

Note: The correct question is given below:

Which best describes why NH4+ can form an ionic bond with Cl-?

Its outermost shell gains one or more electrons from Cl-.

Its positive charge is attracted to the negative charge of Cl-.

It has a negative charge that is spread over the entire ion.

It has a nitrogen atom that is strongly attracted to Cl-.

Its positive charge is attracted to the negative charge of Cl-.

Explanation:

An ammonium ion is a positively charged ion which is composed of a molecule of ammonia and a hydrogen ion which are in a coordinate covalent bond due to the lone pair of electrons of the nitrogen atom in the molecule ammonia. The chloride ion however, has an extra electron which gives it a negative charge.

An ionic bond is formed between two oppositely charged ions by a transfer of electrons from one atom to another. It usually occurs between non-metals and metals. However, that formed between ammonium ion and chloride ion is between non-metals entirely.

Due to electrostatic attraction between the oppositely charged ions, an ionic bond is formed between ammonium ion, NH4+, and chloride ion, Cl-.

Answer:

Don not sure if you got my last email I sent you a text but different question

Answer:

down below

Explanation:

NO

H20

P4O10

SO3

1. NO

2. H2O

3. P4O10

4. SO3

Phosphine is an example of a polar molecule with non-polar bonds

Answer: it is C because it is part of a “animals” body as I would explain it.

Answer:

B. Molecules of different types of atoms that are not attracted to each other.

Explanation:

On a broad basis, matter can be subdivided into pure or distinct substances and impure substances (mixtures);

Pure substances are distinct substances having the following properties:

From this criteria, we see that the second choice is nullified. This is because pure substances have their molecules attracted to each other.

Answer:

The number "1.25" is already at a number that shouldn't be determined using scientific notation. Do you want 1.25ml----> liters ? If so, here

Explanation:

1.25 × [tex]10^{-3}[/tex]

is the amount of liters

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Answer:

38 g?

Explanation:

I'm not entirely sure, but perhaps it is 49 grams x 78.25%? This gives you an answer of 38 g using significant figures.

Answer:

4.D. 2KJ

5.B. close to 0 degree celsius

Explanation:

heat absorbed= heat given out

100g * 4.2 * (x-0)= 400g * 4.2* ( 20-x) where x is the new temp reached

then x= 20

i.e. the temperature of ice increases to 5 degree celsius and the temperature of water decreases to 5 degree celsius .

hope it helps

Answer:

P₂ = 0.99 atm

Explanation:

Given data:

Initial pressure = 1.02 atm

Initial temperature = 11.2°C

Final pressure = ?

Final temperature = 4.00°C

Solution:

Initial temperature = 11.2°C (11.2+273 = 284.2 K)

Final temperature = 4.00°C (4.00+273 = 277 K)

According to Gay-Lussac Law,

The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.

Mathematical relationship:

P₁/T₁ = P₂/T₂

Now we will put the values in formula:

1.02 atm / 284.2 K = P₂/277 K

P₂ = 1.02 atm × 277 K / 284.2 K

P₂ = 282.54 atm. K /293 K

P₂ = 0.99 atm

Answer:

Sound waves and light waves need to change places.

Explanation:

Given table:

           Mechanical waves                        Electromagnetic waves

          Ocean water                                      Sound waves

          Light waves                                        Radiation waves

          Earthquake waves                             X-ray waves

From the given table, to be correct, light and sound waves must change their position.

Light wave is an electromagnetic wave

Sound wave is a mechanical wave

 An electromagnetic wave does not require a material medium for propagation.

  Mechanical waves require material medium for their propagation.

        Mechanical waves                        Electromagnetic waves

          Ocean water                                     Light waves waves

          Sound waves                                         Radiation waves

          Earthquake waves                                 X-ray waves

Answer:

Sound waves and light waves need to change

Explanation:

Answer:

1. Fe₂O₃ + 3CO → 2Fe + 3CO₂

2. Al₂O₃ + 3C + Cl₂ → 3CO + 2AlCl₃

3. 2H₂S + 3O₂ → 2SO₂ + 2H₂O

Explanation:

Para balancear ecuaciones redox se acostumbra a usar el método ion-electrón, hay que determinar qué elemento se oxida y cual se reduce lo que a la vez significa, aumento del número de oxidación o descenso del mismo.

1. Fe₂O₃ + CO → Fe + CO₂

Para este caso, el hierro se reduce, pasando de Fe³⁺ a Fe⁰ o lo que se dice estado fundamental.

Fe³⁺  +  3e⁻  → Fe

El carbono del CO se oxida a CO₂ donde el carbono pasa de C²⁺ a C⁴⁺

C²⁺  →   C⁴⁺ + 2e⁻

Como los electrones quedaron desbalanceados multiplicamos por 2 y 3 las semi reacciones

(Fe³⁺  +  3e⁻  → Fe ) . 2

2Fe³⁺  +  6e⁻  → 2Fe

(C²⁺  →   C⁴⁺ + 2e⁻) . 3

3C²⁺  →   3C⁴⁺ + 6e⁻

Ya podemos balancear la ecuacion final:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

(como ya tenemos 2 atomos de hierro en el oxido, no haría falta agregar el 2 en la estoquiometría)

2. Al₂O₃ + C + Cl₂ → CO + AlCl₃

En este caso el carbono se oxida, y el cloro se reduce

C →  C²⁺  +  2e⁻

Cl₂ + 2e⁻ → 2Cl⁻

Como el cloro es una molécula diatómica por cada cloro que se reduce, tendremos dos cloruros, tomando los 2 electrones que libera el C.

En este caso los electrones están balanceados

Al₂O₃ + C + Cl₂ → CO + 2AlCl₃

Han quedado desbalanceados el C y el O, asi que no queda otra que completar con la estequiometría

Al₂O₃ + 3C + Cl₂ → 3CO + 2AlCl₃

3.  H₂S + O₂ → SO₂ + H₂O

El O₂ se está reduciendo, pasando de 0 a -2

El S del ácido se oxida de +2 a +4

O₂ + 4e⁻ → 2O⁻²

Son dos atomos de O, que cada átomo puede atrapar dos electrones, por ende, consigue enlazar 4 electrones en total

S⁺²  → S⁴⁺ + 2e⁻

Como los electrones quedaron desbalanceados, completamos multiplicando la segunda semi reaccion x2

2S⁺²  → 2S⁴⁺ + 4e⁻

O₂ + 4e⁻ → 2O⁻²

2H₂S + O₂ → 2SO₂ + 2H₂O

Ya que el oxigeno quedó desbalanceado en el lado producto, completamos con la estoquimetría

2H₂S + 3O₂ → 2SO₂ + 2H₂O