Q: Which of the following is a correct example of dimensional analysis for converting $$ 5.0 \ \mathrm{km} to $$meters?

$$ 5.0 \ \mathrm{km} \times \frac{1000 \ \mathrm{m}}{1 \ \mathrm{km}} = 5000 \ \mathrm{m} $$

Question 1

Which of the following best describes a sample of air?

Accepted Answer

A mixture, because it contains several substances physically combined but not chemically bonded.

Question 2

Which of the following is a chemical change?

Accepted Answer

Burning a piece of paper.

Question 3

Balance the following equation: $$ \mathrm{C_2H_6} + \mathrm{O_2$} \rightarrow \mathrm{CO_2$} + \mathrm{H_2O} $$

Accepted Answer

$$ 2\mathrm{C_2H_6} + 7\mathrm{O_2$} \rightarrow 4\mathrm{CO_2$} + 6\mathrm{H_2O} $$

Question 4

Which of the following statements about the periodic table is correct?

Accepted Answer

A group is a vertical column and a period is a horizontal row.

Question 5

Which of the following elements is a transition metal?

Accepted Answer

Iron ($$ \mathrm{Fe} )$$

Question 6

What is the atomic number and mass number of an atom with 17 protons, 18 neutrons, and 17 electrons?

Accepted Answer

Atomic number: 17, Mass number: 35

Question 7

Express $$ 0.000456  in $$scientific notation with the correct number of significant figures.

Accepted Answer

$$ 4.56 	imes 10$$^{-4}$$ $$

Question 8

How many significant figures are in the measurement $$ 0.02030 $$?

Accepted Answer

4

Question 9

Convert $$ 25.0 ^\circ \mathrm{C}  to $$Kelvin.

Accepted Answer

$$ 298.15 \ \mathrm{K} $$

Question 10

A patient receives a medication dose of $$ 0.250 \ \mathrm{g} . $$How many milligrams is this?

Accepted Answer

$$ 250 \ \mathrm{mg} $$

Question 11

A metal cube has a mass of $$ 54.0 \ \mathrm{g} $$ and a volume of $$ 20.0 \ \mathrm{cm}^3 . $$What is its density?

Accepted Answer

$$ 2.70 \ \mathrm{g/cm}^3 $$

Question 12

Which of the following best describes the difference between heat and temperature?

Accepted Answer

Heat is the energy transferred due to a temperature difference, while temperature measures the average kinetic energy of particles.

Question 13

A $$ 50.0 \ \mathrm{g} $$ sample of water is heated from $$ 20.0 ^\circ \mathrm{C}  to$$ $$ 30.0 ^\circ \mathrm{C} . If $$the specific heat of water is $$ 4.18 \ \mathrm{J/g \cdot ^\circ C} $$, how much heat is absorbed?

Accepted Answer

$$ 2090 \ \mathrm{J} $$

Question 14

Which of the following is a correct example of dimensional analysis for converting $$ 5.0 \ \mathrm{km}  to $$meters?

Accepted Answer

$$ 5.0 \ \mathrm{km} 	imes \frac{1000 \ \mathrm{m}}{1 \ \mathrm{km}} = 5000 \ \mathrm{m} $$

Question 15

Which type of radioactive decay results in the emission of a particle with a $$ +2 $$ charge and a mass number of $$ 4 $$?

Accepted Answer

Alpha decay

Question 16

Which of the following correctly represents the beta decay of carbon-14?

Accepted Answer

$$ ^{14}_{6}\mathrm{C} \$$rightarrow ^{14}$$_{7}\mathrm{N} $$+ ^{0}$$_{-1}\mathrm{e} $$

Question 17

A radioactive isotope has a half-life of $$ 3.0 $$ hours. If you start with $$ 80.0 \ \mathrm{mg} $$, how much remains after $$ 9.0 $$ hours?

Accepted Answer

$$ 10.0 \ \mathrm{mg} $$

Question 18

Which of the following statements about gamma radiation is correct?

Accepted Answer

Gamma radiation has no mass and no charge.

Question 19

A sample contains $$ 32.0 \ \mathrm{g}  of a $$radioactive isotope. Its half-life is $$ 2.0 $$ days. How much will remain after $$ 6.0 $$ days?

Accepted Answer

$$ 4.0 \ \mathrm{g} $$

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