The millions of fossils that scientists have collected are called the fossil __.

Answers

Answer 1

Answer:

record

Explanation:


Related Questions

Two liters of hydrogen gas are stored at a
pressure of 100 kPa. If the temperature
does not change, what will the volume
of the gas be when the pressure is
decreased to 25 kPa?

Answers

Answer:

the volume will expand

Explanation:

gas under pressure contracts, and expands with a lesser pressure

The volume of the hydrogen gas at 25 kPa is 8 Liters.

Explanation:

Given:

At constant temperature, 2 liters of hydrogen gas at 100kPa pressure.

To find:

The volume of the hydrogen gas at 25kPa.

Solution:

The initial pressure of the hydrogen gas =[tex]P_1=100 kPa[/tex]

The initial volume of the hydrogen gas at 100 kPa =[tex]V_1=2 L[/tex]

The final pressure of the hydrogen gas =[tex]P_2=25 kPa[/tex]

The final volume of the hydrogen gas at 25kPa = [tex]V_2=?[/tex]

Using Boyles law:

[tex]P_1V_1=P_2V_2\\100kPa\times 2 L=25 kPa\times V_2\\V_2=\frac{100 kPa\times 2L}{25 kPa}=8L[/tex]

The volume of the hydrogen gas at 25 kPa is 8 Liters.

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Write a balanced equation for the complete oxidation reaction that occurs when ethane burns in air

Answers

Balanced equation : 2C₂H₆ (g) + 7O₂ (g) ⟶ 4CO₂ (g) + 6H₂O (ℓ)Further explanation

Alkanes are saturated hydrocarbons that have single bonds in chains

General formula for alkanes :

[tex]\tt \large{\bold{C_nH_{2n+2}}[/tex]

Hydrocarbon combustion reactions (specifically alkanes)

[tex]\large {\box {\bold{C_nH _ (_2_n _ + _ 2_) + \dfrac {3n + 1} {2} O_2 \Rightarrow nCO_2 + (n + 1) H_2O}}}[/tex]

So that the burning of ethane with air (oxygen):

[tex]\tt C_2H_6+\dfrac{7}{2}O_2\rightarrow 2CO_2+3H_2O[/tex]

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

or we can use mathematical equations to solve equilibrium chemical equations by giving the coefficients for each compound involved in the reaction

C₂H₆ (g) + aO₂ (g) ⟶ bCO₂ (g) + cH₂O (ℓ)

C : left 2, right b ⇒ b=2

H: left 6, right 2c⇒ 2c=6⇒ c= 3

O : left 2a, right 2b+c⇒ 2a=2b+c⇒2a=2.2+3⇒2a=7⇒a=7/2

What is the volume, in liters, of 1.40 mol of oxygen gas at 20.0°C and 0.974 atm?

Answers

Answer:

V = 34.55 L

Explanation:

Given that,

No of moles, n = 1.4

Temperature, T = 20°C = 20 + 273 = 293 K

Pressure, P = 0.974 atm

We need to find the volume of the gas. It can be calculated using Ideal gas equation which is :

PV=nRT

R is gas constant, [tex]R=0.08206\ L-atm/mol-K[/tex]

Finding for V,

[tex]V=\dfrac{nRT}{P}\\\\V=\dfrac{1.4\times 0.08206\times 293}{0.974 }\\\\V=34.55\ L[/tex]

So, the volume of the gas is 34.55 L.

Can you explain what vsepr stand for in your own word?

Answers

Answer:

VSEPR stands for: valence-shell electron-pair repulsion. Which is the study of the molecular geometry. Basically, it accounts for the geometry arrangements of electron pairs around the central atom in terms of the electrostatic repulsion between electron pairs.

What is the product of Na +CaSO4,

Answers

Answer:

Na + CaSO4 = Na2SO4 + Ca

Explanation:

single displacement (substitution)

A piece of wood that measures 2.7 cm x 5.5 cm x 3.9 cm has a mass of 84 g what is the density of the wood

Answers

The density of the wood : 1.45 g/cm³

Further explanation  

Density is a quantity derived from the mass and volume  

Density is the ratio of mass per unit volume  

With the same mass, the volume of objects that have a high density will be smaller than objects with a smaller type of density  

The unit of density can be expressed in g/cm³ or kg/m³  

Density formula:  

[tex]\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}[/tex]

ρ = density  

m = mass  

v = volume  

Volume of the wood

[tex]\tt V=2.7\times 5.5\times 3.9=57.915~cm^3[/tex]

density

[tex]\tt \rho=\dfrac{m}{V}\\\\\rho=\dfrac{84~g}{57.915~cm^3}=\boxed{\bold{1.45`g/cm^3}}[/tex]

Sugar is added to iced tea and the contents are stirred until all of the sugar dissolves. How would the tea now be classified?

Answers

By concentrating the mixes of substances

PLEASE HURRY WILL GIVE BRAINLIEST

Click Oil Basics and use the information to complete this passage that discusses how plastic production affects society.

The production of plastics makes life
{answer} , so it benefits society. On the other hand, the production of plastics causes air and water {answer} , so it also harms society.

Answers

Answer:

easier and pollution

Explanation:

I just had this question and got it right

A metal block, 2.0cm x 2.5cm x 3.0cm, has a mass of 40.5g. What is the density of the sample? What type of metal is the metal block composed of?

Aluminum - 2.699
Copper - 8.92
Iron - 7.874
Lead - 11.43
Nickel - 8.908
Tin - 7.265
Zinc - 7.14

Answers

Answer:

The block is made up of aluminum.

density = 2.7 g/cm³

Explanation:

Given data:

Dimension of metal block = 2.0 cm×2.5 cm× 3.0 cm

Mass of block = 40.05 g

Density of block = ?

Which metal is this = ?

Solution:

Density:

Density is equal to the mass of substance divided by its volume.

The symbol used for density is called rho. It is represented by ρ. However letter D can also be used to represent the density.

Units:

SI unit of density is Kg/m3.

Other units are given below,

g/cm3, g/mL , kg/L

Formula:

D=m/v

D= density

m=mass

V=volume

Volume of block = 2.0 cm×2.5 cm× 3.0 cm = 15 cm³

d = m/v

d = 40.5 g/ 15 cm³

d = 2.7 g/cm³

The block is made up of aluminum.

1. Compare and contrast the characteristics of metals and nonmetals.
2. Describe the electrochemical series and why it’s important in understanding metals.
3. Describe the theory of ionization in regard to acids and bases.
4. Identify the role of indicators.

Answers

Answer:

1. Both metals and nonmetals are types of elements and can be involved in chemical reactions. Some of their differences are highlighted in the chart below.

  Metals:    

Appearance; Shiny.    

Conduct heat or electricity; Yes.  

Malleable or ductile; Yes, both and has great mechanical strength.    

Form stable compounds; Forms stable compounds with acids; also forms oxides; replaces hydrogen in acids or water; combine with nonmetals; often becomes positive.

  Nonmetals :  

Appearance; Not shiny .  

Conduct heat or electricity; Not well .  

Malleable or ductile; Brittle and not easily molded into shapes .  

Form stable compounds; Oxides usually give acid reactions in water; often becomes negative

2. The electrochemical series is an arrangement of metals in such order that any metal in the list is displaced from its compounds by any metal above it, but displaces any metal below it. The higher up the list a metal is, the greater its activity. Knowing a metal’s placement on this chart can help you understand the activity of the metal, especially in regard to its ability to displace hydrogen in acids. Any items on the list far above hydrogen will do a good job at displacing it, those near it won’t do such a good job, and those below it won’t displace it from acids at all.

3. When placed in water, acids dissociate and form free hydrogen ions, which determine the properties of acids. The number of hydrogen ions determines the strength of an acid. Strong acids dissociate to a large degree and produce a large number of hydrogen ions. Weak acids dissociate to only a slight degree.

When placed in water, bases dissociate and form free hydroxyl ions, which determine the properties of bases. Strong bases dissociate to a great degree and produce a large number of hydroxyl ions. Weak bases dissociate to only a slight degree.

When free hydrogen ions and free hydroxyl ions are removed from solutions of acids and bases, then the acidic and basic properties disappear. This is what happens when acids and bases are mixed together in proper proportion; the hydroxyl ion will unite with the hydrogen ion to form water. The resulting salt product is neutral.

4. Indicators are used to help determine the pH value of an unknown solution. These are often papers that turn a certain color at certain pH values.

Metals are good conductors of heat and electricity but the non-metals are not.

Compare metals and non-metals

Metals are good conductors of electricity and heat whereas non-metals are poor conductors of heat and electricity. Metals have high density while on the other hand, non-metals have low density. Metals are malleable and ductile whereas non-metals are brittle.

So we can conclude that metals are good conductors of heat and electricity but the non-metals are not.

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A substance absorbed 895 J and caused its temperature to increase by 10 ºC. If the substance has a mass of 27.9 g, what is the substance's specific heat in J/(gºC) ?

1.) 3.21

2.) 4.62

3.) 1,406.25

4.) 249,705

Answers

Answer:

i dont get the equation sorry wish i can help

4.62 is the correct answer

A foam square has a mass of 25 g and a volume of 90 mL. What is the density?

Answers

Answer:

The answer is 0.28 g/mL

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

So we have

[tex]density = \frac{25}{90} = \frac{5}{18} \\ = 0.277777...[/tex]

We have the final answer as

0.28 g/mL

Hope this helps you

How many total atoms of element X are represented below?

Answers

It’s 4 on the left and 2 on the right so 6 altogether

Select the correct answer

Which statement best supports the idea that water conservation is important for human societies?

OA Once humans use water, it cannot be reused ever again,

OB. Only about 1% of the freshwater on Earth is easily accessible.

OC Water is constantly being lost from the hydrosphere

OD. Most land animals use salt water instead of freshwater.

Answers

Answer:

Only about 1% of the freshwater on Earth is easily accessible.

Explanation:

Freshwater accounts for a minimal proportion of water resources on planet earth. About 70 percent of the world surface area  is covered by water, but only  about 2.5 percent of this mass of water is fresh. The remaining are marine or salt water. Amazingly, just about 1 percent of this  freshwater is easily accessible. The other 1.5% is trapped in glaciers and snowfields.

This underscore the need for water conservation on the planet since fresh water is a scarce resource and people living in many areas have no access to fresh water.

Does changing the number of protons change the identity of the element you have built ?

Answers

Answer: Yes.

Explanation:

the number of protons in the nucleus determines an element's identity. Chemical changes do not affect the nucleus, so chemical changes cannot change one type of atom into another. The number of protons in a nucleus does change sometimes, however. The identity of the atom, therefore, changes.

a piece of metal has a mass of 1.3 g/cm and a has a volume of 24.9 cm3 what is its mass

Answers

Answer:

34.611g

Explanation:

mass of metal = ?

density of metal = 1.39/cm³

volume = 24.9 cm³

density = mass/volume

mass = density × volume

= 1.39g/cm³ × 24.9 cm³

= 34.611g

Which statement best defines potential enregy?

A. Potential energy is stored energy.

B. Potential energy is energy that can change over time.

C.Potential energy is the energy of motion.

D. Potential energy is the type of energy a roller coaster uses.

Answers

Answer:

A. Potential energy is stored energy

Explanation:

Answer:

A

Explanation:

i have the same question

Which describes the motion of the car as shown by the graph?
A) travels at a constant speed
B) not moving
C) changing directions
D) speeding up

Answers

D) speeding up I think

what is the concept of the doppler effect?

Answers

Doppler Effect refers to the change in wave frequency during the relative motion between a wave source and its observer. ... For instance, when a sound object moves towards you, the frequency of the sound waves increases, leading to a higher pitch.

how this is helpful!!!!

HELPPP PLEASEEE!!! calculate the energy of radiation with a wavelength of 432 nm

Answers

Formula:


f = C/λ


Where,

λ (Lambda) = Wavelength in meters

c = Speed of Light (299,792,458 m/s)

f = Frequency (MHz)

answer= 693964023.148148 MHz

Protons have about the same mass as:

A. plasma particles
B. neutrons
C. electrons

Answers

the answer is B. neutrons

Calculate the density of an object with mass = 30.50 g and a volume = 2.20 cm^3​

Answers

Answer:

The answer is 13.86 g/cm³

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question

mass = 30.5 g

volume = 2.2 cm³

We have

[tex]density = \frac{30.5}{2.2} \\ = 13.863...[/tex]

We have the final answer as

13.86 g/cm³

Hope this helps you

PLZ ANSWER WILL GIVE BRAINLIEST ASAP
Given the data below, what substance does not show a reaction for any of the tests? Hint: (+)= reaction occurred, (-)= no reaction

unknown
salt
Corn starch
Gelatin

Answers

Answer:

Salt

Explanation:

It has all -

1. True or False? The scientific method is defined as a method of research
in which a problem is identified, data is gathered, and a hypothesis is
created based off the data, then the hypothesis is tested.

Answers

Answer:

true

Explanation:

please mark BRAINLIEST

Which option is an example of a chemical property?
A. boiling point
B. ability to react with oxygen
C. color
D. density

Answers

Answer:

boiling point

Explanation:

Option B

A sound wave has a frequency of 20 Hz and a wavelength of 100 m. What is speed of the wave

Answers

The speed of a wave can be calculated using this formula:

v = f x λ

Where:

v is the wave speed in metres per second, m/s

f is the frequency in hertz, Hz

λ (lambda) is the wavelength in metres, m

Calculation:

Given:

f = 20 Hz

λ = 100m

Using the equation:

v = f x λ

v = 20 x 100

v = 2000 m/s

Therfore, the speed of the wave is 2000 m/s

A sound wave has a wavelength of 100 m and a frequency of 20 Hz. The wave's speed is 2× 10^3 m/s.

assuming frequency = 20 Hz and wavelength = 100 m

utilized concept: v= = 20×100 = 2×10³ m/s

Why is frequency important?

The frequency in physics is the quantity of waves passing a fixed location in a unit of time. It also indicates how many cycles or vibrations a body in periodic motion experiences in a given unit of time.

How would you define sound?

A sort of energy created by vibrations is sound. The molecules of the air surrounding an item vibrate as a result.. These molecules vibrate because they collide with nearby molecules, which also vibrate as a result.

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What is involved in weathering?

Answers

Answer:

the answer is water.Hope this helps

PE = mgh, solve for m

Answers

Answer:

P.E. = mgh, where m is the mass in kilograms,

Answer:

[tex]m = \frac{PE}{gh} [/tex]

Explanation:

[tex]if \: PE = mgh \\ then \to \\ m = \frac{PE}{gh} [/tex]

♨Rage♨

With radiocarbon dating, scientists compare an object's carbon-14 levels with _____. the carbon-14 levels of an object from the same time period carbon-14 levels in the atmosphere the carbon-14 levels in the rock surrounding the object the object's carbon-12 levels

Answers

Answer:carbon-14 levels in the atmosphere

Explanation:

When carrying out radiocarbon dating, the level of carbon-14 in a sample is compared with the level of carbon 14 in the atmosphere because, objects exchange carbon-14 with the atmosphere.

Comparison of the activities of carbon-14 in the atmosphere and in the sample gives the age of the sample since the half-life of carbon-14 is a constant.

Sodium + oxygen
What colour is the flame produces

Answers

Answer:

Orange

Explanation:

I used google my b

Answer:

ORANGE

explanation:

Small pieces of sodium burn in air with often little more than an orange glow. Using larger amounts of sodium or burning it in oxygen gives a strong orange flame.

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