law of mass conservation

Matter can not be created nor destroyed: it can only be

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

Tags

NGSS.MS-PS1-5

A chemical reaction is balanced when

• both sides have the same elements

• Both sides have the same number of atoms

Which of these is not a chemical reaction?

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

Tags

NGSS.MS-PS1-2

The number of water molecules in 3H₂O is

• 6

• 2

• 3

• 5

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

Tags

NGSS.MS-PS1-5

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

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

Tags

NGSS.MS-PS1-2

In the reaction AB-----> A + B reactant AB has 12g and product B has 5g. How many grams should product A have?

• 17g
• 2g
• 7g
• None of the above

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How many oxygen atoms are in the products for the chemical reaction below?
 $4Fe\ +\ 3O_{2\ }\rightarrow\ 2Fe_2O_3$  

• 2

• 3

• 5

• 6

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5