Q: A refrigerator uses $$780 \ \mathrm{kWh} of $$electrical energy per year. How many kilocalories of electricity does it use in three years? ($$1 \ \mathrm{kWh} = 3.60 \times 10^6$ \ \mathrm{J}$$, $$1 \ \mathrm{cal} = 4.184 \ \mathrm{J})$$

$$2.01 \times 10^5$ \ \mathrm{kcal}$$

Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more different elements that are chemically bonded together.

Question 2

Which of the following is a homogeneous mixture?

Accepted Answer

Coffee

Question 3

A sample of copper absorbs 3.53 kJ of heat, which increases the temperature by $$25 ^\circ \mathrm{C}. If $$the specific heat capacity of copper is $$0.385 \ \mathrm{J} / \mathrm{g} \cdot ^\circ \mathrm{C}$$, what is the mass (in kg) of the copper sample?

Accepted Answer

$$0.367 \ \mathrm{kg}$$

Question 4

Which of the following is a physical change?

Accepted Answer

Tearing a piece of paper.

Question 5

Which of the following represents a chemical property of hydrogen gas?

Accepted Answer

It reacts explosively with oxygen gas.

Question 6

Which of the following is NOT a physical property?

Accepted Answer

An iron bar rusts.

Question 7

Which of the following is a reversible change?

Accepted Answer

Melting a chocolate bar then re-solidifying it in the freezer.

Question 8

A refrigerator uses $$780 \ \mathrm{kWh} of $$electrical energy per year. How many kilocalories of electricity does it use in three years? ($$1 \ \mathrm{kWh} = 3.60 	imes 10^6$ \ \mathrm{J}$$, $$1 \ \mathrm{cal} = 4.184 \ \mathrm{J})$$

Accepted Answer

$$2.01 	imes 10^5$ \ \mathrm{kcal}$$

Question 9

Which of the following substances will have the lowest observed viscosity?

Accepted Answer

Helium gas

Question 10

Nitric acid has a melting point of $$-42^\circ \mathrm{C}$$ and a boiling point of $$83^\circ \mathrm{C}. $$What is its physical state at $$110^\circ \mathrm{C}$$?

Accepted Answer

Gas

Question 11

Which of the following is NOT a chemical property for an unknown element?

Accepted Answer

It has a yellow-orange color.

Question 12

Which of the following statements deals with potential energy with nonchemical energy associated?

Accepted Answer

Your chemistry book sitting on a table counter near the trashcan weighing $$12 \ \mathrm{N} at a $$height of $$1.2 \ \mathrm{m}.$$

Question 13

Which of the following is a chemical change?

Accepted Answer

Cooking an egg

Question 14

If $$15.7 \ \mathrm{g} of $$silver raises its temperature by $$17.2^\circ \mathrm{C}$$ when it absorbs $$6845.5 \ \mathrm{J}$$, what is its molar heat capacity? (Molar mass of Ag = $$107.87 \ \mathrm{g/mol})$$

Accepted Answer

$$25.5 \ \mathrm{J/mol} \cdot ^\circ \mathrm{C}$$

Question 15

How much heat (in kJ) is released when $$120.0 \ \mathrm{g} H$_2O $$goes from $$90^\circ \mathrm{C} to$$ $$45^\circ \mathrm{C}$$? The specific heat capacity of H$$_2O is$$ $$4.184 \ \mathrm{J/g} \cdot ^\circ \mathrm{C}.$$

Accepted Answer

$$18.8 \ \mathrm{kJ}$$

Question 16

Which of the following best describes the compressibility and viscosity of a solid?

Accepted Answer

Low compressibility, high viscosity

Question 17

At what temperature is the temperature in degrees Fahrenheit equal to the temperature in degrees Celsius?

Accepted Answer

$$-40^\circ$$

Question 18

Which of the following containers would have the greatest flow of thermal energy in the form of heat if all are at $$50^\circ \mathrm{C}$$?

Accepted Answer

120 g H$$_2O$$

Question 19

Which of the following represents a physical property?

Accepted Answer

Mercury is a silvery liquid at $$25^\circ \mathrm{C}.$$

Matter and Energy: Classification, States, Properties, and Changes

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