Q: How many molecules are in 2.00 moles of water ($\mathrm{H_2O}$)? ($1\ \text{mole} = 6.022 \times 10^{23}$ molecules)

$1.204 \times 10^{24}$ molecules

Question 1

Which of the following best describes a scientific law?

Accepted Answer

A summary of many experimental results and observations that describes how things work.

Question 2

A student measures the mass of a sample as 0.00450 g. How many significant figures are in this measurement?

Accepted Answer

3

Question 3

Convert $3.25 	imes 10^4$ to decimal notation.

Accepted Answer

$32,500$

Question 4

Which of the following is a physical property?

Accepted Answer

Color

Question 5

A chemical reaction occurs in a closed container. The mass of the reactants is 12.0 g. After the reaction, the mass of the products is measured. What should the mass of the products be according to the law of conservation of mass?

Accepted Answer

Exactly 12.0 g

Question 6

Which of the following is an example of potential energy?

Accepted Answer

A stretched rubber band

Question 7

Calculate the amount of heat required to raise the temperature of 50.0 g of water from $20.0\ ^\circ\mathrm{C}$ to $80.0\ ^\circ\mathrm{C}$. (Specific heat capacity of water $= 4.18\ \mathrm{J/g\cdot ^\circ C}$)

Accepted Answer

$12,540\ \mathrm{J}$

Question 8

Which statement about protons and neutrons is correct?

Accepted Answer

Neutrons have no charge and are found in the nucleus.

Question 9

What is the atomic number of an element with 17 protons?

Accepted Answer

17

Question 10

A neutral atom of sodium ($\mathrm{Na}$) has an atomic number of 11. How many electrons does it have?

Accepted Answer

11

Question 11

Which of the following is the correct chemical formula for magnesium chloride?

Accepted Answer

$\mathrm{MgCl_2}$

Question 12

What is the molar mass of $\mathrm{CO_2}$?

Accepted Answer

$44.01\ \mathrm{g/mol}$

Question 13

How many molecules are in 2.00 moles of water ($\mathrm{H_2O}$)? ($1\ 	ext{mole} = 6.022 	imes 10^{23}$ molecules)

Accepted Answer

$1.204 	imes 10^{24}$ molecules

Question 14

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

Accepted Answer

$\mathrm{CH_2O}$

Question 15

Which of the following is a double displacement reaction?

Accepted Answer

$\mathrm{AgNO_3} + \mathrm{NaCl} \rightarrow \mathrm{AgCl} + \mathrm{NaNO_3}$

Question 16

Which of the following is a strong electrolyte in aqueous solution?

Accepted Answer

$\mathrm{NaCl}$

Question 17

Which statement correctly describes a redox reaction?

Accepted Answer

Oxidation is the loss of electrons and reduction is the gain of electrons.

Question 18

Which of the following electromagnetic waves has the shortest wavelength?

Accepted Answer

Gamma rays

Question 19

What is the bond angle in a molecule with four electron groups and four bonding groups (tetrahedral geometry)?

Accepted Answer

$109.5^\circ$

Introduction to Chemistry: Comprehensive Study Notes

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