VA SOL Chemistry

A student measures the mass of a 1.00g aluminum rod as 0.99g. The best estimate of the percent error associated with this measurement is -

• 0.01%

• 0.1%

• 1%

• 10%

The most efficient way to determine whether a reaction is an exothermic chemical reaction is to use -

• an oxygen probe

• a temperature probe

• a pressure probe

• a pH probe

Tags

NGSS.HS-PS1-4

Which type of chemical reaction does the equation in the image represent?

• synthesis

• neutralization

• oxidation - reduction

• double - replacement

What is the oxidation number of an oxide ion?

• +1

• +2

• -1

• -2

What is the molarity of a solution with .2 moles of potassium permanganate (KMnO₄) dissolved in enough water to make a 500.0 mL solution

• 0.0004 M

• 0.1 M

• 0.4 M

• 100 M

When 92.0g of ethanol (C₂H₅OH) are vaporized at its boiling point of 78.3^oC, it requires 78.6 kJ of energy. What is the approximate molar heat of vaporization of ethanol in kJ/mol?

• 0.854

• 1.17

• 39.3

• 78.3

Tags

NGSS.HS-PS3-4

Directions: Type your answer in the box. Your answer must use significant digits.

What is the density of an aqueous solution that has a mass of 10.081g and 12.5mL? ____ g/mL

Answer explanation

Density = Mass/volume

The least accurate measurement has 3 significant digits, so the answer should be rounded to three significant digits.

Which element has 16 neutrons, 15 protons, and 15 electrons?

• Sulfur (S)

• Phosphorous (P)

• Gallium (Ga)

• Zinc (Zn)

Tags

NGSS.MS-PS1-1

This equation represents which type of chemical reaction?

• single-replacement

• double-replacement

• decomposition

• synthesis

In the formula for barium chloride, (BaCl₂), barium (Ba) is written first because it is -

• a single atom

• a larger atom

• the positive ion

• the negative ion