Chocolate chip cookie dough is a heterogeneous mixture because its composition varies from one part of the sample to another.
Correct Answer
True
True. A heterogeneous mixture has visibly different regions, and a spoonful of cookie dough may contain more or fewer chips than another. A homogeneous mixture, by contrast, has the same composition throughout.
Category: Classification of Matter
Question 2
A compound can be broken down into simpler substances by chemical changes.
Correct Answer
True
True. A compound is a pure substance of two or more elements chemically combined, and a chemical change such as electrolysis can separate it into its elements. Elements cannot be broken down further by chemical changes.
Category: Classification of Matter
Question 3
Sugar dissolved in water can be separated back into sugar and water only by a chemical change.
Correct Answer
False
False. Sugar water is a mixture, and mixtures can be separated by physical changes; evaporating the water leaves the sugar behind. Only compounds require chemical changes to break them into simpler substances.
Category: Classification of Matter
Question 4
A pure substance has a constant composition in every sample of it.
Correct Answer
True
True. A pure substance, whether an element or a compound, always has the same makeup and properties no matter where the sample comes from. Mixtures can vary in composition.
Category: Classification of Matter
Question 5
A liquid has a definite shape but no definite volume.
Correct Answer
False
False. A liquid has a definite volume but takes the shape of the part of the container it occupies. A solid is the state with both a definite shape and a definite volume.
Category: States of Matter
Question 6
Plasma is a state of matter that contains no electrically charged particles.
Correct Answer
False
False. Plasma is a gaseous state of matter that contains an appreciable number of electrically charged particles. It is found in lightning, the sun and neon-type signs.
Category: States of Matter
Question 7
The law of conservation of matter states that there is no detectable change in the total quantity of matter during a chemical change.
Correct Answer
True
True. In a chemical change the atoms are rearranged but not created or destroyed, so the total mass of the products equals the total mass of the reactants. This holds in a closed system where nothing escapes.
Category: Classification of Matter
Question 8
Density is an extensive property because it depends on the amount of the sample.
Correct Answer
False
False. Density is an intensive property: mass and volume both grow in proportion as a sample grows, so their ratio stays the same. Extensive properties, such as mass and volume themselves, depend on how much matter is present.
Category: Physical and Chemical Properties
Question 9
Melting ice is a chemical change because the water changes from solid to liquid.
Correct Answer
False
False. Melting is a physical change; the substance is still water before and after. A chemical change produces one or more new substances with different compositions.
Category: Physical and Chemical Properties
Question 10
Melting point is a physical property because it can be measured without changing the identity of the substance.
Correct Answer
True
True. A physical property can be observed or measured without forming a new substance, and a melted solid is the same substance in a different state. Chemical properties, such as flammability, can only be observed by changing the substance into something new.
Category: Physical and Chemical Properties
Question 11
The SI base unit of length is the centimeter.
Correct Answer
False
False. The SI base unit of length is the meter. A centimeter is a smaller unit equal to one-hundredth of a meter.
Category: SI Units and Prefixes
Question 12
The metric prefix kilo- represents a factor of 1000.
Correct Answer
True
True. Kilo- means one thousand, so 1 kilometer is 1000 meters and 1 kilogram is 1000 grams. Prefixes let one base unit cover very large and very small quantities.
Category: SI Units and Prefixes
Question 13
One liter is equal to 100 mL.
Correct Answer
False
False. One liter equals 1000 mL because the prefix milli- means one-thousandth. A liter is also equal to one cubic decimeter.
Category: SI Units and Prefixes
Question 14
A temperature of 0 K is equal to 0 degrees Celsius.
Correct Answer
False
False. Zero on the absolute scale, 0 K, equals -273.15 degrees Celsius, the lowest temperature possible. Zero degrees Celsius, the freezing point of water, equals 273.15 K.
Category: SI Units and Prefixes
Question 15
A temperature change of 1 K is the same size as a temperature change of 1 degree Celsius.
Correct Answer
True
True. The kelvin and the degree Celsius are the same size; the two scales differ only in where zero is placed. That is why converting between them only requires adding or subtracting 273.15.
Category: SI Units and Prefixes
Question 16
Zeros between nonzero digits, as in 1.05, are significant.
Correct Answer
True
True. Captive zeros sit between nonzero digits and are always significant, so 1.05 has three significant figures. Leading zeros, as in 0.05, are not significant.
Category: Significant Figures
Question 17
When 2.346 is rounded to three significant figures, the result is 2.34.
Correct Answer
False
False. The digit dropped is 6, which is 5 or greater, so the last kept digit rounds up and the result is 2.35. A dropped digit less than 5 would leave the kept digit unchanged.
Category: Significant Figures
Question 18
In scientific notation, 0.000560 is written as 5.60 x 10^-4.
Correct Answer
True
True. Moving the decimal point four places to the right gives 5.60, so the exponent is -4. The trailing zero is kept because it is significant, giving three significant figures in both forms.
Category: Significant Figures
Question 19
The relationship 1 in = 2.54 cm limits a converted result to three significant figures.
Correct Answer
False
False. The inch is defined as exactly 2.54 cm, so this factor is an exact number with unlimited significant figures. The significant figures of the result are set by the measured value being converted.
Category: Measurement Calculations
Question 20
A measurement reported as a number with a unit, such as a mass of 3.2 g, is quantitative information.
Correct Answer
True
True. Quantitative observations include numbers, usually with units, while qualitative observations describe properties such as color or odor without numbers. Measured data are the quantitative side of the scientific method.
Category: Scientific Method