Equations-ID and Balance

Which of the following is evidence that a chemical change has taken place?

• change in color from mixing

• change in size or volume

• change in shape

• change in energy (temperature)

When dry ice (solid carbon dioxide) sublimes it goes directly from a solid to a gas. What type of change is occurring? 

• Chemical change
• Physical change
• None of the above 

Tags

NGSS.MS-PS1-4

How many oxygen atoms are present in the following? 
4Ca(OH)₂

• 4
• 6
• 8
• 1

Tags

NGSS.MS-PS1-1

Why must we balance chemical equations? (choose the BEST answer)

• Our teacher said so

• to abide by the law of conservation of energy

• to abide by the law of conservation of mass

Which of the following is true?

• Na is a gas at room temperature

• Cl combusts when put in water or air

• NaCl is very different than the elements Na and Cl

• Cl is a metal and a solid

 Fill in the blank to balance the chemical equation. 
2KI  +  ____Cl₂ →  2KCl  +  I₂

• 1
• 2
• 3
• 4

Tags

NGSS.MS-PS1-5

What coefficient should go in the blank space to balance the chemical equation? 
2Al  +____  HCl   →    2AlCl₃  +  3H2

• 2
• 4
• 3
• 6

Tags

NGSS.MS-PS1-5

Which of the following shows the correct way to balance the chemical equation?
Fe + O₂ -> Fe₂O₃

• 4Fe + 3O₂ -> 2Fe₂O₃
• 2 Fe + 3O₂ -> Fe₂O₆
• 4 Fe + O₆ -> 2Fe₂O₃
• None of the options are correctly balanced.

Tags

NGSS.MS-PS1-5

What is the left part of a chemical equation called?
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

What does the Law of Conservation of Mass state?

• Matter cannot be gained or lost in a chemical reaction.
• Matter can only be lost in a chemical reaction.
• Matter can only be gained in a chemical reaction.
• Matter can be gained and lost in a chemical reaction. 

Tags

NGSS.MS-PS1-5