Quiz  /  Law of Mass Action Class 6 MCQ Questions With Answers

  • 1. 
    This type of system allows matter to flow freely in and out...

  • Closed System
  • Open System

  • 2. 
    According to the Law of Conservation of Mass, what happens to the wood and oxygen when it is burned?

  • The wood disappears.
  • It stays the same chemically.
  • The atoms in the wood and oxygen rearrange and form smoke and ash.
  • Nothing.

  • 3. 
    Which are the reactants in the following reaction?2Mg + O2 ---> 2MgO

  • Mg and O
  • MgO
  • Mg and MgO
  • O and MgO

  • 4. 
    What do we call the chemicals that result from a chemical reaction?

  • reactants
  • products
  • subscripts
  • coefficients

  • 5. 
    Measure of the amount of matter

  • mass
  • volume
  • weight
  • density

  • 6. 
    What will weigh more when a chemical change is complete? The reactants before the chemical reaction, or the product after the reaction is complete?

  • They both will weigh the same
  • The product always weighs more than the reactant
  • The reactant will weigh more than the product
  • They both will loose mass after the reaction

  • 7. 
    Jamie weighs a glass of water and observes its weight to be 12 ounces. Jamie then adds 6 ice cubes to the glass of water. Each ice cube weighs one ounce. After all of the ice cubes have melted, what will be theapproximate weight of the glass of water?

  • 6
  • 12
  • 18 ounces

  • 8. 
    What is the Law of Conservation of mass?

  • Mass is created in a chemical reaction
  • Mass is created in a physical change
  • New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
  • Mass is never created or destroyed

  • 9. 
    The coefficient in 3H2O is

  • 6
  • 2
  • 3
  • 5

  • 10. 
    A chemical reaction is balanced when

  • both sides have the same elements
  • Both sides have the same  number of atoms
  • Same subscripts
  • Same coefficients

  • 11. 
    A boiling pot with a lid on it to keep in the energy is what type of system?

  • Closed System
  • Open System

  • 12. 
    A precipitate is a

  • liquid that forms when two solids are reacted
  • a solid that forms when two liquids are mixed
  • a gas that forms when vinegar and baking soda react
  • a change of color in a solution

  • 13. 
    The Law of Conservation of Mass States

  • Energy cannot be created nor destroyed, it can only change form.
  • Mass cannot be created nor destroyed, it can only change form.
  • Mass can be created or destroyed, it cannot change form.

  • 14. 
    Which of these is not a chemical reaction?

  • Burning of wood
  • Milk going bad
  • Mixing vinegar and baking soda
  • Melting of ice

  • 15. 
    In a reaction A + B ----> C, reactant A has 5g and product C has 9g. How many grams does reactant B should have?

  • 4g
  • 5g
  • 9g
  • 14g

  • 16. 
    If reaction starts with 20g of reactants it should produce

  • a total of 40g of products
  • a total of 10g of products
  • a total of 80 g of products
  • a total of 20g of products

  • 17. 
    The law of conservation of mass states that ________

  • the total mass of reactants is more than the total mass of products
  • the mass of a chemical reaction is not constant
  • the mass of a chemical reaction remains constant
  • the total mass of reactants is less than the total mass of products

  • 18. 
    Since gasses weigh nothing, when they are produced in a reaction they do not have to be accounted for.

  • True
  • False

  • 19. 
    The number in front of a compound or element is a

  • Subscript
  • Coefficient
  • Superscript
  • Charge

  • 20. 
    P4 + 3 O2 ---> 2 P2O3

  • Single Replacement
  • Combustion
  • Synthesis
  • Decomposition

  • 21. 
    In a synthesis reaction

  • A compound breaks apart into two or more compounds
  • Two or more compounds make one single product
  • CO2 and H2O must be products
  • O2 must be a reactant

  • 22. 
    A student mixes 125 grams of sugar, 250 grams of water and 5 grams of flavoring. The solution weighs...

  • 250 grams
  • 380 grams
  • 375 grams
  • 400 grams

  • 23. 
    What types of systems are there?

  • Mechanical and Electrical Systems
  • Inside and Outside Systems
  • Open and Closed Systems
  • Human and Machine Systems

  • 24. 
    Matter can not be created nor destroyed: it can only be

  • Destroyed a little bit
  • Invisible
  • Transformed, changed
  • None of the above

  • 25. 
    The number to the lower side of an element is a

  • Subscript
  • Superscript
  • Coefficient
  • Charge

  • 26. 
    ________ are the starting substances in a chemical equation.

  • Reactants
  • Producer
  • Reaction
  • Products

  • 27. 
    O3 ---> O + O2

  • Synthesis
  • Single Replacement
  • Decomposition
  • Combustion
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