$CATEGORY: Science - Khan Academy/1.Chemical Reactions and Equations/1.Chemical Reactions and Equations--Chemical Equations

//Multiple Choice

What is the chemical equation for the reaction of hydrogen and oxygen? {
    =2H₂ + O₂ \= 2H₂O
    ~H₂ + O₂ \= H₂O
    ~2H₂O + O₂ \= H₂
    ~2H₂ + 2O₂ \= H₂O
}

What is produced in the reaction 2H₂ + O₂ \= 2H₂O? {
    ~Hydrogen
    ~Oxygen
    =Water
    ~Energy
}

What does the subscript '2' in H₂ represent? {
    ~The number of molecules
    =The number of hydrogen atoms in one molecule
    ~The number of oxygen atoms
    ~The number of water molecules
}

In the reaction 2H₂ + O₂ \= 2H₂O, how many moles of hydrogen are required to produce 2 moles of water? {
    ~1 mole
    =2 moles
    ~3 moles
    ~4 moles
}

Which of the following is considered a molecule or a compound? {
    ~Molecular hydrogen (H₂)
    ~Molecular oxygen (O₂)
    =Water (H₂O)
    ~Nitrogen (N₂)
}

What happens if the reaction between hydrogen and oxygen does not occur? {
    ~We would have no life.
    ~The universe would cease to exist.
    ~Water would not exist.
    =All of the above.
}

In the reaction 2H₂ + O₂ \= 2H₂O, how many oxygen atoms are involved? {
    ~1
    =2
    ~4
    ~6
}

What is one use of the reaction 2H₂ + O₂ \= 2H₂O? {
    =Producing energy for rocket fuel
    ~Making carbon dioxide
    ~Producing nitrogen gas
    ~Creating acids
}

How many hydrogen atoms are in 2 molecules of hydrogen gas (H₂)? {
    ~2
    =4
    ~6
    ~8
}

What does the equation 2H₂ + O₂ \= 2H₂O demonstrate about atoms? {
    ~Atoms are created during the reaction.
    ~Atoms are destroyed during the reaction.
    =Atoms are rearranged to form new substances.
    ~Atoms disappear during the reaction.
}

Which of the following is the main reason hydrogen and oxygen are used together as rocket fuel? {
    ~They create a stable reaction at low temperatures.
    =The reaction produces a large amount of heat and energy.
    ~They are inexpensive to obtain.
    ~The reaction is slow and controlled.
}


//True or False

The reaction 2H₂ + O₂ \= 2H₂O produces hydrogen gas as a product. {F}

The number of atoms of each element is conserved in the reaction 2H₂ + O₂ \= 2H₂O. {T}

Oxygen molecules (O₂) consist of two oxygen atoms. {T}

Hydrogen gas (H₂) is typically found as individual hydrogen atoms in nature. {F}

Energy is not needed for the reaction between hydrogen and oxygen to occur. {F}

The reaction 2H₂ + O₂ \= 2H₂O produces no energy. {F}

The reaction between hydrogen and oxygen is essential for life on Earth. {T}

The reaction 2H₂ + O₂ \= 2H₂O produces oxygen as a product. {F}

//Match the following

Match the following items from Column A with their correct corresponding options from Column B\:
{
= Hydrogen (H₂) -> A Reactant
= A Product -> Water (H₂O)
= Energy -> Produced during reaction as by product
= Arrow in a chemical equation -> Indicates the direction of the reaction
= H₂O (Water) -> Compound of hydrogen and oxygen
}



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