Law of conservation of mass

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

• transformed from one form to another
• duplicated
• vanished
• multiplied

If reaction starts with 20g of reactants it should produce 

• 20g of products
• 40g of products
• 10g of products
• 30g of products

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

Bob puts 200 grams of ice into a pitcher with 900 grams of water. He gets distracted and comes back later to find that the ice has melted in the water. How many grams of water does Bob now have in the pitcher?

• 1000 grams
• 1100 grams
• 1200 grams
• 900 grams

__ are the starting substances in a chemical equation.

• Reactants
• Products
• Coefficients
• Subscripts

Considering the reaction given , how much zinc was present in the zinc carbonate?

• 64 grams

• 110 grams

• 104 grams

• 50 grams

How many oxygen atoms are in 
Fe(NO₃)₂

• 2
• 3
• 6
• 12

4 grams of hydrogen and 32 grams of oxygen will combine to form:

• 36 grams of water
• 36 grams of hydrogen peroxide
• 32 grams of water
• 36 grams of oxygen

Which  of the following is a balanced equation?

• 2H2 + O2 = 2H2O
• H2 + O2 = H2O
• 2H2 + 2O2 = 2H2O
• H2 + 2O2 = H2O

In a chemical reaction, 4 grams of sodium must combine with how many grams of chlorine to produce 10 grams of table salt?

• 6 grams
• 10 grams
• 4 grams
• 8 grams