Q: Convert $$0.000345\ \mathrm{m} to $$scientific notation.

$$3.45 \times 10$$^{-4}$$\ \mathrm{m}$$

Q: A sample contains $$2.50\ \mathrm{mol} of$$ $$\mathrm{CO_2$}. $$What is the total number of molecules present? ($$N_A = 6.022 \times 10$$^{23}$$\ \mathrm{mol}^{-1})$$

$$1.51 \times 10$$^{24}$$ molecules

Question 1

Which of the following statements best describes the difference between a scientific law and a scientific theory?

Accepted Answer

A scientific law is a summary of observed behavior, while a scientific theory provides an explanation for that behavior.

Question 2

Which of the following is a chemical change?

Accepted Answer

Iron rusting in moist air

Question 3

A sample of gold has a mass of $$96.5\ \mathrm{g}$$ and a volume of $$5.00\ \mathrm{cm}^3. $$What is the density of gold in $$\mathrm{g/cm}^3$$?

Accepted Answer

$$19.3\ \mathrm{g/cm}^3$$

Question 4

Which of the following substances is a homogeneous mixture?

Accepted Answer

Air

Question 5

Convert $$0.000345\ \mathrm{m} to $$scientific notation.

Accepted Answer

$$3.45 	imes 10$$^{-4}$$\ \mathrm{m}$$

Question 6

Which of the following statements about protons, neutrons, and electrons is correct?

Accepted Answer

Protons are positively charged and found in the nucleus.

Question 7

A neutral atom of $$^{23}_{11}\mathrm{Na}$$ contains how many protons, neutrons, and electrons?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 8

Which of the following elements is a halogen?

Accepted Answer

Chlorine ($$\mathrm{Cl})$$

Question 9

Which of the following elements exists as a diatomic molecule in nature?

Accepted Answer

Oxygen ($$\mathrm{O}_2)$$

Question 10

Which of the following is the correct formula for the ionic compound formed between magnesium and nitrate?

Accepted Answer

$$\mathrm{Mg(NO_3$)_2}$$

Question 11

A compound is analyzed and found to contain only carbon and hydrogen. Which of the following best describes this compound?

Accepted Answer

It is a covalent compound.

Question 12

Which of the following is the correct name for $$\mathrm{Na_2SO_4}$$?

Accepted Answer

Sodium sulfate

Question 13

What is the charge on the ion formed by aluminum?

Accepted Answer

$$3+$$

Question 14

Which of the following is a physical property?

Accepted Answer

Melting point

Question 15

A student measures the mass of a sample three times and gets values very close to each other, but far from the true value. This is an example of:

Accepted Answer

High precision, low accuracy

Question 16

Which of the following is the correct conversion for $$25.0\ ^\circ\mathrm{C} to $$Kelvin?

Accepted Answer

$$298\ \mathrm{K}$$

Question 17

Which of the following is a correct statement about allotropes?

Accepted Answer

Allotropes are different forms of the same element in the same physical state.

Question 18

A sample contains $$2.50\ \mathrm{mol} of$$ $$\mathrm{CO_2$}. $$What is the total number of molecules present? ($$N_A = 6.022 	imes 10$$^{23}$$\ \mathrm{mol}^{-1})$$

Accepted Answer

$$1.51 	imes 10$$^{24}$$ molecules

Question 19

Which of the following ions is a polyatomic ion?

Accepted Answer

$$\mathrm{NO_3$^-}$$

Question 20

A solution is prepared by dissolving $$5.00\ \mathrm{g} of $$salt in $$100.0\ \mathrm{g} of $$water. Which term best describes this system?

Accepted Answer

Homogeneous mixture

General Chemistry Study Notes: Matter, Measurement, Elements, and Compounds

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