A magnet was placed near a pile that contained both iron and sulfur. The magnet was moved gradually closer to the pile. As it neared the pile, the magnet started attracting small pieces of iron from the pile. Which of these statements best describes the contents of the pile?

Answer:

t(half-life) = 1600 yrs

Explanation:

All radio decay follows 1st order kinetics and therefore can be applied to the expression A = A₀e^(-kt)

A = current activity

A₀ = initial activity

k = decay constant

t = time of decay

Half-Life = 0.693/k

k = ln(A/A₀) / -t = ln(0.25) / -3200yrs = 4.33x 10⁻⁴ yrs⁻¹

Half-Life => t(1/2) = (0.693/4.33 x 10⁻⁴)yrs⁻¹ = 1600 yrs.

Answer:

b

Explanation:

Answer:

Ionization energy

Electron affinity

Electronegativity

Explanation:

Answer:

It's called a theory because it has not been proven yet. so we can not claim it to be a fact without proof.

Answer: There is no concrete evidence.

Explanation: If we could do an experiment and create the Big Bang and watch it happen and study it, it would be law. It's for the same reason that evolution is considered a theory. We are not watching it take place and there is no eye witness account of evolution happening because evolution happens over millions and millions of years. If we could sit here and watch the universe be created without need for simulations or theories, then it would be law.

Answer:

Molecules are made of two or more atoms

Molecules are made of atoms of the same element or different elements.

Molecules range in size.

Explanation:

A molecule is formed whenever two or more atoms combine. Hence we can define a molecule as a combination of two or more elements that are combined chemically and can not be separated by any physical means.

Molecules may be composed of the same atoms as in O2, F2 etc or different atoms as in CO2, H2O, etc.

The sizes of molecules differ. Some molecules are quite small in size while others are quite large in size.

Answer:

Molecules are made of two or more atoms

Molecules range in size

Molecules are made of atoms of the same element or different elements.

1. 18 L

2. 20.832 L

Given

Combustion of ethane

Required

Volume of CO₂

Solution

Avogadro's Law :

In the same T,P and V, the gas contains the same number of molecules  

So the ratio of gas volume will be equal to the ratio of gas moles  

V₁/n₁=V₂/n₂

1. From equation, mol ratio of C₂H₆ : CO₂ ⇒ 2 : 6

so the volume of CO₂ :

= 6/2 x 6 L

= 18 L

2. mol ethane (MW=32 g/mol) :

= mass : MW

= 10 g : 32 g/mol

= 0.31

mol CO₂ :

= 6/2 x 0.31

= 0.93

The volume CO₂(assume at STP) = 20.832 L

Answer:

B

Explanation:

hope this helps :)

Salt added : 14.5 g

Given

17% salt solution

71 ml water

Required

salt needed

Solution

%mass = (mass solute : mass solution) x 100%

71 ml water = 71 g water(density = 1 g/ml)

mass solute = x

[tex]\tt 17\%=\dfrac{x}{x+71}\times 100\%\\\\0.17(x+71)=x\\\\0.17x+12.07=x\\\\0.83x=12.07\\\\x=14.5[/tex]

Answer:

ΔT = 0.78 °C

Explanation:

Given data:

Mass of Al = 9.5 g

Specific heat capacity of Al = 0.9 J/g.°C

Temperature change = ?

Heat added = 67 J

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

67 J = 9.5 g × 0.9 j/g.°C × ΔT

67 J = 85.5 j/°C × ΔT

ΔT = 67 J  /  85.5 j/°C

ΔT = 0.78 °C

Answer:

i believe its 1.56

Explanation:

Answer: 55.233 moles of oxygen will react with 500 g of hexane.

Explanation:

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of hexane = 500g

Molar mass of hexane = 86 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of hexane}=\frac{500g}{86g/mol}\\\\\text{Moles of hexane}=5.814mol[/tex]

The chemical equation for the reaction of burning of hexane in air follows:

[tex]2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O[/tex]

By stoichiometry of the reaction:

2 moles of hexane reacts with 19 moles of oxygen

So, 5.814 moles of hexane will react with = [tex]\frac{19}{2}\times 5.814=55.233moles[/tex] of oxygen

Hence, 55.233 moles of oxygen will react with 500 g of hexane.

Answer:

Mass = 96 g

Explanation:

Given data:

Mass of oxygen required = ?

mass of Al = 110 g

Solution:

Chemical equation:

4Al + 3O₂     →     2Al₂O₃

Number of moles of Al:

Number of moles = mass/molar mass

Number of moles = 110 g/ 27 g/mol

Number of moles = 4 mol

Now we will compare the moles of Al and oxygen.

                     Al           :           O₂

                      4            :          3

Mass of oxygen:

Mass = number of moles × molar mass

Mass = 3 mol ×  32 g/mol

Mass = 96 g

Answer:

486 grams

Explanation:

No of moles = mass in gram / molar mass

Mass in gram = No of moles × molar mass

Molar mass of CaCO3 = 40+12+(16*3)

= 40+12+48 = 100 amu

Mass in gram = 4.86 × 100

Mass in gram 486 grams

Answer:

C) The nuclear waste leaked into groundwater, and exposed humans to radiation that could potentially cause cancer.

Explanation:

your welcome girlies <33

The nuclear waste leaking into groundwater and exposing humans to radiation was how nuclear plant impacted the human population.

This is referred to a thermal power station in which the heat source is a nuclear reactor with radioactive elements.

The waste leaked into groundwater, and exposed humans to radiation that could potentially cause cancer which was how it affected the surrounding human population and why option C was chosen.

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Answer:

P =  14.1 atm    

Explanation:

Given data:

Mass of methane = 64 g

pressure exerted by water vapors = ?

Volume of engine = 24.0 L

Temperature = 515 K

Solution:

Chemical equation:

CH₄ + 2O₂      →      CO₂ + 2H₂O + energy

Number of moles of methane:

Number of moles = mass / molar mass

number of moles = 64 g/ 16 g/mol

Number of moles = 4 mol

Now we will compare the moles of water vapors and methane.

              CH₄          :            H₂O  

                 1            :             2

                 4            :         2/1×4 = 8 mol

Pressure of water vapors:

PV = nRT

R = general gas constant = 0.0821 atm.L/mol.K

P = 8 mol × 0.0821 atm.L/mol.K× 515 K / 24.0 L

P = 338.25 atm.L/ /  24.0 L

P =  14.1 atm      

Explanation:

Rubidium is in Group 1 and exists as Rb+ ions.

Sulfur is in Group 16 and exists as S2- ions.

To form a compound containing rubidium and sulfur, the charges of the ions must be equal.

Therefore there are 2 rubidium and 1 sulfur atoms.

=> Chemical formula is Rb2S.

Sodium is also in Group 1 and exists as Na+ ions.

Oxygen is also in Group 16 and exists as O2- ions.

Therefore there are 2 sodium and 1 oxygen atoms.

=> Chemical formula is Na2O.

The chemical formula of the compounds form are as follows;

Discussion:

To form a compound between rubidium and sulfur, the net charge must be zero

As a result, we need 2 rubidium and 1 sulfur atoms.

Similarly, Sodium, Na is in Group 1 and ionises as Na+ ions.

Oxygen, O is in Group 16 and ionises as O2- ions.

To form a compound between Sodium and Oxygen, the net charge must be zero

As a result, we need 2 Sodium and 1 Oxygen atoms.

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Answer: The correct answer is option A. [tex]Na^+\text{ and }Cl^-[/tex]

Explanation:

An ionic compound is defined as the compound formed by the complete transfer of electrons from one element (forming cation) to another element (forming anion)

Sodium (Na) is an element having atomic number 11 and its electronic configuration is [tex]1s^22s^22p^63s^1[/tex]

It will loose 1 electron to form [tex]Na^+[/tex] ion (cation)

Chlorine (Cl) is an element having atomic number 17 and its electronic configuration is [tex]1s^22s^22p^63s^23p^5[/tex]

It will gain 1 electron to form [tex]Cl^-[/tex] ion (anion)

The ionic compound so formed will have the chemical formula of NaCl.

Hence, the correct answer is option A. [tex]Na^+\text{ and }Cl^-[/tex]

Answer:

Na

Explanation:

Na Because it's exist in group 1

Answer:

la tabla de la derecha muestra una lista de los elementos ordenados por su energía de ionización. El elemento de mayor energía de ionización es el Helio, y el de menor el Cesio. La unidad de energía de ionización es el electrón voltio (eV).

Answer:

See explanation

Explanation:

In the Rutherford experiment, alpha particles were directed at the same spot on a thin gold foil.

As the alpha particles hit the foil, most of the alpha particles went through the foil. In Rutherford's interpretation, most of the particles went through because the atom consisted largely of empty space.

However, some of the alpha particles were deflected through large angles, in Rutherford's interpretation, the deflected alpha particles had hit the dense positive core of the atom which he called the nucleus.

This accounted for their scattering through large angles throughout the foil in all directions.

Explanation:

covalent bonds

Two covalent bonds form between the two oxygen atoms because oxygen requires two shared electrons to fill its outermost shell.

Answer:

I think is answer B

but you can chek

Answer:

C

Explanation:

All salts are ionic compounds. Think about NaCl. Na+ is a cation and Cl- is an anion. NaCl form an ionic compound and are then considered a salt.

Answer:

1. Temp of gas 21C, 6.2

2.Temp of gas 294, Volume of gas 0.78cm3

Explanation:

Just answered on Edge

Answer:

picture

Explanation:

edge 2021

Answer:

Solid

Explanation:

because their molecules are tightly packed.

According to the forces of attraction, at  room temperature, the greatest attractive forces exist between particles of a solid.

Forces of attraction  is a force by 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 gases  as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.

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

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Explanation:

a) K(s) + I2(s)  --> KI(s)

The balanced equation is;

2K(s) + I2(s)  --> 2KI(s)

b) Mg(s)  +  Br2(l)  --> MgBr2(s)

The balanced equation is;

Mg(s)  +  Br2(l)  --> MgBr2(s)

c) KBr(aq)  +  AgNO3(aq)  --> KNO3(aq)  + AgBr(s)

The balanced equation is;

KBr(aq)  +  AgNO3(aq)  --> KNO3(aq)  + AgBr(s)

d) KClO3(s)  --> KCl(s)  +  O2(g)

The balanced equation is;

2KClO3(s)  --> 2KCl(s)  +  3O2(g)

e) C2H6(g)  +  O2(g)  -->  CO2(g)  + H2O(l)

The balanced equation is;

2C2H6(g)  +  7O2(g)  --> 4CO2(g)  + 6H2O(l)

f) Al(s)  +  O2(g)  --> Al2O3(s)

The balanced equation is;

4Al(s)  +  3O2(g)  --> 2Al2O3(s)

g) P4(s)  +  H2(g)  --> PH3(g)

The balanced equation is;

P4(s)  +  6H2(g)  --> 4PH3(g)

Answer:

Answer 1

light energy from the sun.

answer 2

Microscopic organisms are tiny life forms, often consisting of a single cell. ... Algae — these are single celled plants also known as phytoplankton (from the Greek, meaning drifting plants)

answer 3

Some phytoplankton are bacteria, some are protists, and most are single-celled plants. Among the common kinds are cyanobacteria, silica-encased diatoms, dinoflagellates, green algae, and chalk-coated coccolithophore

Explanation:

it uses light to convert water and carbon dioxide molecules into glucose (sugar molecule) and oxygen

1 sodium bromide

2 scandium

3 aluminium selenide

4 sodium fluoride

5 potassium chloride

6 strontium fluoride

7 magnesium bromide

8 sodium oxide

9 lithium oxide

10

11 lithium fluoride

12 calcium bromide

13 methyl beta-d-glucopyeanoside

14

15sodium chloride and 16 sodium nitrate

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