$CATEGORY: Science - Khan Academy/9.Heredity & Evolution/9.Heredity & Evolution--Fossils

//Multiple Choice

The method used to determine the age of fossils is called\: {
    =Fossil dating
    ~Thermometry
    ~Fossilization
    ~Crystallization
}

Which dating method is used to determine the age of very old fossils? {
    =Uranium-lead dating
    ~Carbon dating
    ~Water displacement method
    ~Magnetism dating
}

The half-life of carbon-14 is approximately\: {
    =5,700 years
    ~2,000 years
    ~10,000 years
    ~1 million years
}

Fossils older than 50,000 years cannot be dated using\: {
    =Carbon dating
    ~Uranium dating
    ~Potassium-argon dating
    ~Rubidium-strontium dating
}

The principle of superposition states that\: {
    =Younger rock layers are on top of older layers
    ~Older rock layers are above younger layers
    ~All fossils are the same age
    ~Fossils form in igneous rocks
}

Which gas is released during carbon dating? {
    =Carbon dioxide
    ~Oxygen
    ~Nitrogen
    ~Hydrogen
}

Which isotope is commonly used in radiocarbon dating? {
    =Carbon-14
    ~Carbon-12
    ~Oxygen-16
    ~Hydrogen-2
}

Fossils that are used to determine the relative age of rock layers are called\: {
    =Index fossils
    ~Trace fossils
    ~Cast fossils
    ~Mold fossils
}

The uranium-lead dating method is most useful for dating rocks that are\: {
    =Older than 1 million years
    ~Less than 10,000 years old
    ~Found only in ocean beds
    ~Recently formed
}

Which of the following is NOT a radiometric dating method? {
    =Tree-ring dating
    ~Carbon dating
    ~Potassium-argon dating
    ~Uranium-lead dating
}


//True or False

Fossil dating is used to determine the age of living organisms. {F}

Carbon dating is useful for fossils older than 1 million years. {F}

The law of superposition helps in determining relative fossil age. {T}

Radioactive decay occurs at a constant rate. {T}

Carbon-14 dating is useful for fossils less than 50,000 years old. {T}

Fossils can be dated using uranium isotopes. {T}

Radiometric dating measures the decay of radioactive elements in fossils. {T}

The half-life of a radioactive element changes over time. {F}

Index fossils help in determining the absolute age of rock layers. {F}

Fossils provide evidence of past life and evolution. {T}


//Fill in the blanks

The technique used to determine the age of fossils is called {
~ Thermometry
~ Fossilization
= Fossil dating
~ Crystallization
}

The half-life of carbon-14 is ______ years. {
~ 2,000 
= 5,700 
~ 10,000
~ None of the above
}

Fossils provide evidence of ______. {
= Evolution 
~ Magnetism 
~ Respiration
~ None of the above
}

The isotope used in carbon dating is ______. {
~ Carbon-12 
= Carbon-14 
~ Oxygen-16
~ None of the above
}

A fossil older than 1 million years is usually dated using ______ dating. {
= Uranium-lead
~ Carbon 
~ Nitrogen
~ None of the above
}

The law of superposition states that younger rocks are found ______. {
~ Below 
= Above 
~ Mixed with older rocks
~ None of the above
}

The age of fossils can also be estimated by dating the ______ in which they are found. {
= Sediments 
~ Air 
~ Water
~ None of the above
}

______ fossils are used as markers to determine the relative age of rock layers. {
~ Trace 
= Index 
~ Cast
~ None of the above
}

Fossils that are less than 50,000 years old are usually dated using ______. {
= Carbon dating 
~ Uranium dating 
~ Potassium dating
~ None of the above
}

The process by which radioactive isotopes decay over time is called ______. {
= Radioactivity
~ Fossilization
~ Magnetism
~ None of the above
}

//Numericals

A fossil contains 25% of its original carbon-14. If the half-life of carbon-14 is 5,700 years, how old is the fossil? {
    =11,400 years
    ~5,700 years
    ~17,100 years
    ~22,800 years
}

A fossil has 12.5% of its original carbon-14. How many half-lives have passed? {
    =3
    ~2
    ~4
    ~5
}

The half-life of an isotope is 4,000 years. If a sample has decayed to 1/8 of its original amount, how old is the sample? {
    =12,000 years
    ~8,000 years
    ~16,000 years
    ~20,000 years
}

A fossilized tree is 228 million years old. What dating method was likely used? {
    =Potassium-argon dating
    ~Carbon dating
    ~Uranium-lead dating
    ~Tree-ring dating
}

A rock sample has 50% of its radioactive isotope remaining. If the half-life is 10,000 years, how old is the sample? {
    =10,000 years
    ~5,000 years
    ~20,000 years
    ~40,000 years
}


//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{
    =Fossilization -> Process of fossil formation
    =Paleontology -> Study of fossils
    =Sedimentary rocks -> Contain most fossils
    =Carbon dating -> Determines the age of fossils
}


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