Quiz 1: Law of Conservation of Mass

How many Hydrogen are in 4H₂O?

• 6
• 8
• 2
• 4

How many Oxygen are in H₂O?

• 1
• 2
• 0
• 4

2H₂ + O₂ ----> 2H₂O What is the product?

• ------>
• 2H₂O
• 2H₂+ O₂

2H₂ + O₂ --------> 2H₂O What  are the reactants?

• ----->
• 2H₂O
• 2H₂ +O₂

How many oxygen atoms are in Al₂(SO₄)₃

• 4
• 12
• 7
• 24

How many atoms are there TOTAL in:
H₂SO₄

• 6
• 5
• 7
• 3

Does the equation H₂+O₂ →H₂O follow the Law of Conservation of Mass?

• Yes, because the atoms are equal.

• No, because more info is needed.

• No, because there are more atoms in the product.

• No, because there are more atoms in the reactant.

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

A student heated a 10 gram sample of a chemical in an open container. A chemical reaction occurred, and the mass of the sample was measured again. The mass of the sample was found to be less than before the reaction. Which of the following best explains the decrease in mass of the sample?

• The heat caused the chemical to become less dense.

• The reaction gave off more heat than was added.

• Some of the lighter particles were destroyed.

• Some of the particles escaped as a gas formed.

What does the number ₃ represent in 4NH₃?

• Subscript

• Superscript

• Coefficient