Chemistry Semester 1 Exam Review

An unknown substance can not be easily separated. Would the explanation that this substance is an element be valid?

• No, because the substance could be a compound, which also cannot be separated by physical means.

• No, because the substance could be homogeneous mixture.

• Yes, because elements cannot be separated by ordinary chemical means.

• Yes, because the substance could be homogeneous mixture.

How many significant figures are in the measurement 811.40 grams?

• two

• three

• four

• five

What is the measurement 1042 L rounded off to two significant digits?

• 1.0 x 10³ L

• 1040 L

• 1050 L

• 1.1 x 10³ L

What is the density of an object having a mass of 8.0 g and a volume of 25 cm³ ?

• 0.32 g/cm³

• 2.0 g/cm³

• 3.1 g/cm³

• 200 g/cm³

Which state of matter is characterized by having an indefinite shape, but a definite volume?

• gas

• liquid

• solid

• none of these

Tags

NGSS.MS-PS1-4

Which of the following is a physical change/

• corrosion

• explosion

• evaporation

• rotting of food

Which of the following CANNOT be classified as a substance?

• table salt

• air

• nitrogen

• gold

As a consequence of the discovery of the nucleus by Rutherford, which model of the atom is thought to be true?

• Protons, electrons, and neutrons are evenly distributed throughout the volume of the atom.

• The nucleus is made of protons, electrons, and neutrons.

• Electrons are distributed around the nucleus and occupy almost all the volume of the atom.

• The nucleus is made of electrons and protons.

Tags

NGSS.HS-PS1-8

What does the number 84 in the name krypton-84 represent?

• the atomic number

• the mass number

• the sum of protons and electrons

• twice the number of protons

Air is a mixture not a compound because

• it can be heated to a higher temperature.

• it can be compressed to a smaller volume.

• Its components are chemically combined.

• Its composition can vary.