Question 1

Which of the following best describes the difference between precision and accuracy in scientific measurements?

Accepted Answer

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close measurements are to the true value.

Question 2

A student measures the mass of a sample as $$12.345 g$$, $$12.346 g$$, and $$12.344 g. $$The true mass is $$12.400 g. $$Which statement is correct about the student's measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Convert $$25.0$$ miles to kilometers. (Given: $$1$$ mile $$= 1.609 km)$$

Accepted Answer

$$40.2 km$$

Question 4

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

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 5

An atom has $$17$$ protons and $$18$$ electrons. Which of the following is correct?

Accepted Answer

It is an anion with a $$-1$$ charge.

Question 6

Which of the following is the correct formula for a compound formed between magnesium and nitrogen?

Accepted Answer

$$\mathrm{Mg}_3\mathrm{N}_2$$

Question 7

Calculate the average atomic mass of chlorine if $$75.78\% of $$chlorine atoms have a mass of $$34.969$$ amu and $$24.22\%$$ have a mass of $$36.966$$ amu.

Accepted Answer

$$35.45$$ amu

Question 8

Which of the following best describes an empirical formula?

Accepted Answer

It shows the simplest whole-number ratio of atoms in a compound.

Question 9

A compound has a molecular formula of $$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6. $$What is its empirical formula?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 10

Which of the following is a property of nonmetals?

Accepted Answer

They tend to gain electrons to form anions.

Question 11

Which of the following ions has the same number of electrons as a neutral atom of neon?

Accepted Answer

$$\mathrm{Na}^+$$

Question 12

A sample contains $$3.01 	imes 10$$^{23}$$ atoms of carbon. How many moles of carbon are present?

Accepted Answer

$$0.500$$ mol

Question 13

Which of the following best explains why noble gases are chemically unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 14

Which of the following is the correct name for $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 15

A patient is given a saline solution containing $$0.90\%$$ NaCl by mass. If the patient receives $$500 g of $$solution, how many grams of NaCl did they receive?

Accepted Answer

$$45 g$$

Question 16

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 17

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

$$\mathrm{(NH}_4)_2\mathrm{SO}_4$$

Question 18

A sample of a compound contains $$40.0\%$$ carbon, $$6.7\%$$ hydrogen, and $$53.3\%$$ oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 19

Which of the following best describes the process of dimensional analysis?

Accepted Answer

It is a technique for converting units using conversion factors.

General Chemistry Exam 1 Study Guide: Matter, Measurements, Atoms, Molecules, and Ions

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