chem chapter 2

Which of the following statements is false?

"2 A2B + Energy → 2 A2 + B2" is an example of an exothermic reaction

The formula of most elements is the same as the symbol of the element. This indicates that the element is stable as a single __(i)__, the smallest unit particle of the element. Other elements exist as stable, distinct, and independent __(ii)__, which are made up of two or more atoms.

(i) atom; (ii) molecules

Consider the following image. Which of the following most accurately describes the change represented in the image?

A chemical change which does not follow conservation of mass.

What type of pure substance can be decomposed chemically into other pure substances?

A compound

Which of the following is not a particulate sample of matter?

A human egg cell

Which of the following does not describe a mixture?

Distinct set of physical and chemical properties

Which of the following is the best statement of the Law of Conservation of Energy?

Energy is neither created nor destroyed in an ordinary change

Which of the following is false?

If there is only one atom of an element in a formula unit, it is indicated with a subscript "1"

Which of the following is the best statement of the Law of Conservation of Mass?

In a chemical change, mass is neither created nor destroyed

Which of the following statements is false?

Kinetic energy is always greater than potential energy for an object

Which state of matter is illustrated below?

Liquid

Why do chemists use models of atoms and molecules?

Matter at the particulate level is too small to be seen

Consider the particulate-level illustration: Which is the best classification of this particle?

Molecule

Under what condition is the Law of Conservation of Energy not obeyed?

Nuclear changes

Identify the reactants and the products in the equation H2SO4 + BaCl2 → BaSO4 + 2 HCl.

Reactants: H2SO4 and BaCl2 Products: BaSO4 and HCl

When coasting on a bicycle on a level street, the bicycle will eventually come to a stop. Which of the following is the best explanation for this apparent violation of the Law of Conservation of Energy?

The kinetic energy is converted into an equal amount of energy in other forms

Which of the following statements is false?

The properties of a compound vary

When freshly cut sodium metal is exposed to air, the mass of the substance increases. Which of the following is the best explanation for this apparent violation of the Law of Conservation of Mass?

The sodium reacts with a component of the air, and the total mass of the reactants is equal to the total mass of the products

When room temperature solutions of vinegar and drain cleaner are combined, the temperature of the resulting solution is greater than room temperature. Which of the following is the best explanation for this apparent violation of the Law of Conservation of Energy?

The total energy of the original solutions is equal to the total energy of the resulting solution plus the heat energy

Which of the following correctly describes a homogeneous sample?

Uniform appearance and composition throughout

When paper is burned, the mass of the remaining ash is less than the mass of the original paper. Which of the following is the best explanation for this apparent violation of the Law of Conservation of Mass?

When invisible substances are taken into account, the total mass of the reactants is equal to the total mass of the products

Identify the product(s) that is/are (a) compound(s) in the equation Zn + CoCl2 → ZnCl2 + Co.

ZnCl2

Which of the following particulate-level picture might be associated with the name "silver"?

all the same looking balls clumped together

Which of the following correctly matches each sample with its classification as macroscopic, microscopic, or particulate? Macroscopic Microscopic Particulate

cat hair plant cell protein molecule

Which of the following changes is/are endothermic for the underlined object? i. baking a potato ii. a person being burned by a pan iii. a wood log burning iv. a lit light bulb shining v. a person digesting food

i and ii

Which of the following are compounds? i. Carbon dioxide ii. Silicon iii. Sodium carbonate iv. I2 v. Cr

i and iii

Which of the following substances is/are homogeneous? i. Mineral oil ii. A plant leaf iii. Sausage iv. Sugar v. Freshly squeezed lemonade

i and iv

Which of the following can be a pure substance? i. Gold ii. Air iii. Homogenized milk iv. Sugar completely dissolved in water v. Ice

i and v

Which of the following changes is/are classified as physical?

i and v

Which of the following properties is/are classified as physical? i. The odor of glass cleaning solution ii. The color of chlorine gas iii. The electrical conductivity of copper wire iv. The ability of milk to sour v. A compound does not react with bromine

i, ii, and iii

Which of the following are elements? i. KOH ii. Ne iii. CO iv. Carbon tetrachloride v. Calcium

ii and v

Which of the following changes is/are exothermic for the underlined object? i. ice melts ii. hot french fries cool iii. a beaker warms as chemicals react within it iv. a hot plate warms a beaker of water v. water evaporates off of skin

ii only

Which of the following properties is/are classified as chemical? i. The taste of honey ii. The ability of hair to stretch iii. The corrosive character of hydrochloric acid iv. The combustibility of ethanol v. The softness of talc

iii and iv

Which of the following substances is/are heterogeneous? i. Gasoline ii. A gold bar iii. A freshly opened can of cola iv. Potato chips v. A bacon strip

iii, iv, and v

Which of the following changes is/are classified as chemical? i. Dissolving vinegar in water ii. Evaporation of rubbing alcohol iii. Crushing rock iv. Fermenting apple juice v. Softening a glass tube by heating it

iv only

Examine the apparatus shown in the following image. This apparatus would useful in which of the following separations?

rubbing alcohol from a mixture of rubbing alcohol and water

Which of the following would be classified is a mixture of an element and a compound?

two balls one ball

Consider the particulate-level illustration: Which is the best classification of this particle-level illustration?

Crystalline solid

Most methods for separating mixtures into their components depend on which of the following?

Differing physical properties among the components

In which of the following pairs of substances will there be a net attractive electrostatic force?

A negatively charged piece of dust and a positively charged piece of dust

Which is the best definition of the term model, as it is used in chemistry?

A representation of something else

Examine the following particulate-level representation. This change might be shown symbolically as which of the following?

Agcl+Nal

Which of the following does not describe the gaseous state?

All describe the gaseous state

Which of the following does not describe the liquid state?

All describe the liquid state

A book is pushed off a table, and it falls to the floor. Which of the following statements about the book is false?

All of the above are true

Which of the following is false?

All of the above are true

Which of the following statements is false?

As a positively charged object moves toward a negatively charged object, their potential energy increases

Which of the following properties is distillation based upon?

Boiling points

Which of the following correctly represents electrostatic forces?

Both + going opposite directions

Which of the following is a chemical property?

Combustibility