quiz 1 for chem 100 complete exam written questions and answers

which physical form of matter has a definite volume, but no definite shape? - correct answers Liquid is a physical form of matter that has a definite volume, but no definite shape. A solid has a definite volume and a definite shape and a gas has no definite volume or shape. what physical state of matter is associated the particles having least amount of thermal energy? - correct answers solid solids have the most rigidly packed particles (molecules, ions, or atoms) becaue they have the lowest amount of thermal energy. matter that will take the shape of its container, but not expnd to fill it is what phase? - correct answers liquid Liquids have a definite volume, but no definite shape. This means that they will expand to fit the shape of their container. Which of the following states of matter can exert pressure? - correct answers solid, liquid, & gas Examples of heterogenous mixure - correct answers salad dressing is an example of a heterogeneous mixure as it has a varied composition throughout. which of the following can be broken down into elements by chemical means? - correct answers A compound can be broken into two or more lements by chemical means. An element and atom are already in their most simple forms and cannot be broken down further. A mixure can be separated by physical changes rather than chemical. if something is a compound it is also - correct answers pure substance Pure substances are either elemnts or compunds. A compound is a pure substance composed of more than one element. A compound is no ta mixure because mixtures can be separated by physical means. Since a compound is composed of more than one type of atom it cannot be a single atom. a____ conatins more than one substance as part of its composition - correct answers mixture A mixture conatins more than one type of element or compound. A mixture can be categorized as homogenous or heterogenous depending on whether it has a uniform composition or not. examples of homogeneous mixtures - correct answers maple syrup, air a homogenous mixure varies from a heterogenous mixture in that a homogenous mixure has properties that.. - correct answers do not vary in the mixture Which is an eample of a physical property? - correct answers boiling point, melting point, color During a ____process the identity of the molecule__ - correct answers Chemical;changes During a chemical process the identity of the molecule changes . A chemical change always produces one or more types of matter that differ from the matter present before the change in order to identify a chemical property of matter one thing scientist might look for is - correct answers scientists look for a chemical change such as the formation of a precipitate during a reaction What can be observed without changing the composition of matter? - correct answers boiling point a chemical change occurs as a result of a chemical reaction - correct answers physical process - correct answers the identity of the molecule does not change can separate mixtures chemical process - correct answers can separate pure substances A measurement is ________ if it yields similar results when repeated. - correct answers precise Which of the following must be true about a precise measurement? - correct answers It typically contains many significant figures. A precise measurement has a high degree of certainty, as indicated by having many significant figures. The digits in a measurement, including the uncertain last digit, are known as - correct answers significant figures When determining significant figures within a number, non-zero digits are: - correct answers always significant Explain when trailing zeros should be considered significant. - correct answers when the number includes a decimal point. If the number has a decimal point, then all trailing zeros are significant. For example 3200., 320.0 and 0.03200 are all numbers that have two non-zero digits and two significant trailing zeros, for a total of four significant digits. If there is no decimal point, as in 3200, then the trailing zeros are considered either ambiguous or not significant (opinions vary), but never considered to be significant. The number of significant figures in a value is a display of the _________ of a measurement. - correct answers answer=precision Accuracy is a measure of how close a measurement is to a true or accepted value, whereas precision is a measure of how well consecutive measures of the same quantity agree with one another. The number of significant figures in a value will provide information regarding the precision of the value. For example, 15.000mL is a more precise value than 15mL. Significant figures alone will not provide evidence to suggest that a measured value is close to the true or accepted value. 0.738×0.28 is 0.20664 but is rounded to 0.21. Which rule or rules are applied to this calculation? Select all that apply. - correct answers Round the result to the same number of significant figures as the value with the least number of significant figures. Round up if the digit to be dropped is 5 or greater. For multiplication and division, we round the result to the same number of significant figures as the value with the least number of significant figures. In this calculation, this means rounding to two significant figures by dropping all of the digits after and including the 6 in the thousandths place and rounding up to 0.21. All of the following are rules for rounding numbers when considering significant figures EXCEPT: - correct answers answer=For multiplication and division, round the result to the same number of digits as the number with the most number of significant figures.All of these are rules for rounding significant figures except for the second option. The result should be rounded to the same number of digits as the number with the LEAST number of significant figures. addition and subtraction, round the result to the same number of decimal places as the number with the least number of decimal places. For multiplication and division, round the result to the same number of digits as the number with the most number of significant figures. Round down if the digit to be dropped is less than 5. Round up if the digit to be dropped is more than 5. For a number written in scientific notation, 1.02×10−7, what does the exponent represent? - correct answers answer=the power of ten the digit term is multiplied by In scientific notation, the digit term (also known as the mantissa) is the number before the times symbol, and it gives the precise value of the number. The exponent (b) gives the order of magnitude of the number (power of 10) and can be used to count the number of decimal shifts from the mantissa to write the number in standard notation. The radius of a hydrogen atom is about 0.m. Select this value in scientific notation. - correct answers he magnitude of this number is less than 1, so the exponent will be negative. Move the decimal point to the right until the number has a single digit in the ones place. In this case, the decimal point is moved 11 places to the right to get the number 3.7, so the exponent is −11. Therefore 0.=3.7×10−11 A meteorite was found to weigh 63,500 grams. How many kilograms is this? - correct answers answer=63.5kg The prefix "kilo" means 103, so 1kg=1×103g. To convert grams to kilograms, move the decimal point to the left 3 places and then use the prefix symbol, k, to represent 103. 63,500g= 63.5×103g=63.5kg What is the SI unit used to measure temperature? - correct answers Kelvin is the SI unit for measuring temperature. Joule is an SI unit, but is used to measure energy. Which of the following is NOT considered a SI unit of measurement? - correct answers The meter, the kilogram, and the second are SI units, whereas the pound is not. The pound is part of the Imperial, or US, system of measurements. A power plant delivers about 21,000,000,000,000watts of electricity. Write this quantity in terawatts. - correct answers answer=21 The prefix "tera" means 1012, so 1TW=1012W. To convert watts to terawatts, move the decimal point to the left 12 times, filling in or removing zeros as needed, and then use a prefix symbol, T, to represent 1012. 21,000,000,000,000W=21×1012W=21TW What is the unit used for measuring current in the SI system? - correct answers The ampere is the base unit for electric current in the SI system. Candela and meter are the SI units for luminous intensity and length, respectively. The SI unit for mass is the kilogram. Which of the following is NOT a SI base unit? - correct answers "oz" is the abbreviation for ounce, which is not a SI base unit of measurement. "cd" is for candela, "m" is for meter, and "s" is for second. Which of the following is NOT a base unit used in the SI system of measurement? - correct answers The second, the mole, and the meter are all SI base units. Milliliter is a prefixed unit, with the base unit of "liter." Which is the shortest length of time? - correct answers A nanosecond is 10−9 seconds, whereas a microsecond is 10−6 seconds, a millisecond is 10−3 seconds, and a decisecond is 10−1 seconds. Which prefix means one one-hundredth? - correct answers answer=centi Deci is one tenth, milli is one one-thousandth, and kilo is one thousand. Which is the longest distance? - correct answers A terameter is 10^12 meters, whereas a megameter is 10^6 meters and a kilometer is 10^3 meters. If a scientist wanted to determine the amount of space occupied by an object, she would measure its: - correct answers She would measure the object's volume to determine the amount of space it occupies. If she wanted to determine the amount of matter in an object she would measure the mass and if she wanted to determine the size of the object she would measure the length In what temperature scale does water freeze at 273.15? - correct answers Water freezes at 273.15 K in the Kelvin Scale. Water freezes at 32 ∘F on the Fahrenheit scale and at 0 ∘C on the Celsius scale. What is the standard SI unit of mass? - correct answers The standard SI unit of mass is the kilogram. The gram and the pound are also units of mass but only the kilogram is the SI unit of mass. The meter is the SI unit of length. What is significant about the temperature of 0K? - correct answers It is the temperature at which atoms stop moving. A temperature of 0K is absolute zero and is the point at which motion of atoms stop. Today, the meter is based on: - correct answers the distance light travels in a particular fraction of a second In some cases, volume can be found by cubing which of the following quantities? - correct answers length Volume can be considered length times width times height, or a length in each of three spatial dimensions. Which statement BEST explains why temperature is an intensive property? - correct answers It is a property that is independent of the amount of matter in a sample. Temperature is an intensive property because it is independent of the amount of matter for a given sample. The temperature scale we use most frequently in chemistry labs is: - correct answers The Kelvin scale is used most often in equations because it is an absolute temperature scale, but Celsius is most often used in the lab. Fahrenheit is rarely used in the field of chemistry. If you are asked to report a temperature in base SI units, which scale might you use? - correct answers While Celsius is commonly used in science, kelvin is actually the base SI unit of temperature. A temperature change of one degree kelvin is the same magnitude as a change of - correct answers one degree Celsius Kelvin and Celsius have degrees of the same magnitude, they simply have different starting points, 0 K and −273∘C are both equal to absolute zero. A thermometer reads 25∘C. If the temperature in the room is then increased by 16 K, what temperature will the thermometer read, in degrees Celsius? - correct answers The magnitude of 1K is equal to the magnitude of 1∘C. Therefore, this temperature can be found by adding the temperature change, in Kelvin, to the temperature in Celsius. 25∘C+16K=41∘C If we wish to convert a value in years into days, a conversion factor we could use would be: - correct answers 365 days/1 year The top and the bottom must be equal to each other, so 365 days and 1 year, as those represent the same length of time. In addition, days must be on top and years on the bottom so that we can appropriately cancel out the existing unit. The speed of light is around 6.706×108 miles per hour. What is the speed of light in units of miles per minute? - correct answers To find the speed of light in units of miles per minute, we must use the fact that 60min=1hr. 6.706×10^8mihr×1hr60min=1.118×107mimin Therefore, we find that the speed of light is approximately 1.118×107 miles per minute. In dimensional analysis, what is a conversion factor? - correct answers Conversion units are ratios of physical quantities used to compare between two desired units. They are not experimental or theoretical. In which temperature scale is the boiling point of water represented by the largest number? - correct answers The boiling point of water is 100 Celsius, 212 Fahrenheit, and 373 Kelvin. Therefore the boiling point of water is represented by the largest number on the Kelvin scale. Which operation is performed to convert a temperature given in degrees Celsius to a temperature in kelvin? - correct answers add 273 Kelvin and Celsius have a linear relationship, but not a proportional relationship. They do not have the same starting point, but they increase at the same rate. 0 K is absolute zero, which is about −273∘C, so to get Kelvin from Celsius, add 273. Which of the following temperatures are equivalent to absolute zero (0 K)? Select all that apply. - correct answers −273.15∘C −459.67∘F When computing using dimensional analysis: - correct answers unit conversions can be done either simultaneously or separately We can perform unit conversions one at a time or many at a time, just be sure to keep in mind that this could create a discrepancy in the number of significant figures in your result, depending on when you decide to round your value. The side length of the larger cube is 2.5 times that of the smaller. Since the volume of a cube is equal to the side length cubed, the volumes will be related by a factor of (2.5)3. (2.5)3=15.625which, rounded to three significant figures, is15.6. The volume of the larger cube is about 15.6 times the volume of the smaller cube. - correct answers Dimensional analysis can be used to compute: - correct answers answer=all of the above the density of objects the cost of a list of groceries the distance a car can travel given the available funds all of the above If object A and object B have the same density, but object A has greater mass, then object A must have: - correct answers If these objects have the same density, that means they have the same ratio of mass to volume, so a greater mass must also mean a greater volume.