Es

You mix colourless solution A and B in a beaker. Which of the following observations does not help you prove that a chemical reaction has occurred?

• The beaker becomes warm.

• You see gas bubble out of solution.

• Solution A, solution B, and the mixture are all yellow.

• None of the above; all help prove that a chemical reaction has occurred.

Tags

NGSS.MS-PS1-2

Which of the following indicates that a chemical equation is balanced?

• The numbers of atoms of each element are the same on both sides of the equation.

• All of the coefficients are the same.

• The numbers of molecules on each side of the equation are equal.

• The sums of the coefficients on each side of the equation are equal.

Tags

NGSS.HS-PS1-7

From a complete and correctly written chemical equation, you can obtain the

• chemical formulas of the reactants and products

• relative amounts of the reactants and products

• physical states of the reactants and products

• All of the above

To balance a chemical equation, you must

• adjust the subscripts

• adjust the number of products

• adjust the number of reactants

• adjust the coefficients

In the expression 3CO₂, the numbers 3 and 2 are, respectively,

• a subscript and a coefficient

• a coefficient and a subscript

• two subscripts

• two coefficients

What is the total number of molecules that is represented by the following chemical equation?

2H₂ + O₂ --> 2H₂O

• 3

• 4

• 5

• 16

Tags

NGSS.MS-PS1-1

Which equation below violates the law of conservation of mass?

• 2H₂ + O₂ --> 2H₂O

• KCl + Br --> KBr + Cl₂

• 2Fe₂O₃ + 3C --> 4Fe + 3CO₂

• Na₂CO₃ + 2HCl --> 2NaCl + H₂O + CO₂

Tags

NGSS.HS-PS1-7

Which of the following equations represents the balanced equation for the reaction of iron and oxygen?

• 2Fe + O₂ --> Fe₂O₃

• Fe + 3O₂ --> Fe₂O₃

• 4Fe + 3O₂ --> 2Fe₂O₃

• 3Fe + 3O₂ --> 2Fe₂O₃

Tags

NGSS.HS-PS1-7

Which coefficients correctly balance the formula equation below?

KClO₃(s) --> KCl(s) + O₂(g)

• 1, 1, 1

• 1, 1, 3

• 2, 2, 3

• 2, 1, 1

Tags

NGSS.HS-PS1-7

Which equation is not balanced?

• 2H₂ + O₂ --> 2H₂O

• 4H₂ + 2O₂ --> 4H₂O

• H₂ + H₂ + O₂ --> H₂O + H₂O

• 2H₂ + O₂ --> H₂O

Tags

NGSS.HS-PS1-7