Q: A patient receives a medication dosed at 5.0 mg/kg. If the patient weighs 154 lb, how many milligrams of medication should be administered? (1 kg = 2.205 lb)

$$5.0 \times \frac{154}{2.205} = 350 mg$$

Q: A sample contains $$3.0 \times 10$$^{24}$$ molecules of water. How many moles of water are present? (1$$\ \text{mole} = 6.02 \times $$10^{23}$$ molecules)

$$\frac{3.0 \times 10$$^{24}$$}{6.02 \times 10$$^{23}$$} = 4.98$$ moles

Question 1

Which of the following statements best describes the difference between physical and chemical changes?

Accepted Answer

Physical changes alter the state or appearance of a substance without changing its composition, while chemical changes result in the formation of new substances with different compositions.

Question 2

A patient receives a medication dosed at 5.0 mg/kg. If the patient weighs 154 lb, how many milligrams of medication should be administered? (1 kg = 2.205 lb)

Accepted Answer

$$5.0 	imes \frac{154}{2.205} = 350 mg$$

Question 3

Which of the following ions is polyatomic and carries a -2 charge?

Accepted Answer

$$\mathrm{SO_4$^{2-}}$$

Question 4

Which of the following is the correct electron configuration for a neutral oxygen atom?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 5

A solution has a mass of 250 g and a volume of 200 mL. What is its density?

Accepted Answer

$$\frac{250}{200} = 1.25 g/mL$$

Question 6

Which of the following best describes the term 'isoelectronic'?

Accepted Answer

Atoms or ions that have the same electron configuration.

Question 7

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

Accepted Answer

$$\mathrm{(NH_4$)_2SO_4}$$

Question 8

A radioactive isotope undergoes beta decay. Which particle is emitted and what happens to the atomic number?

Accepted Answer

An electron ($$\beta^-$$ particle) is emitted; atomic number increases by 1.

Question 9

Which of the following is the correct name for $$\mathrm{CO_3$^{2-}}$$?

Accepted Answer

Carbonate

Question 10

How many valence electrons are present in a phosphorus atom?

Accepted Answer

5

Question 11

Which of the following conversions is correct for converting 1.5 L to mL?

Accepted Answer

$$1.5 	imes 1000 = 1500 mL$$

Question 12

Which of the following is the correct formula for the polyatomic ion chlorate?

Accepted Answer

$$\mathrm{$$ClO_3$$^-}$$

Question 13

A compound contains 2.0 moles of sodium and 3.0 moles of chloride ions. How many formula units are present in the sample? ($$1\ 	ext{mole} = 6.02 	imes 10$$^{23}$$ formula units)

Accepted Answer

The number of formula units is determined by the limiting reactant, so $$2.0 	imes 6.02 	imes 10$$^{23}$$ = 1.20 	imes 10$$^{24}$$ formula units

Question 14

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

Accepted Answer

Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other.

Question 15

Which of the following is the correct scientific notation for 0.00056?

Accepted Answer

$$5.6 	imes 10$$^{-5}$$

Question 16

Which of the following elements is most likely to form a $$2^+$$ ion?

Accepted Answer

Magnesium

Question 17

Which of the following is the correct formula for nitrate ion?

Accepted Answer

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

Question 18

Which of the following best describes the trend in atomic radius across a period in the periodic table?

Accepted Answer

Atomic radius decreases from left to right.

Question 19

A sample contains $$3.0 	imes 10$$^{24}$$ molecules of water. How many moles of water are present? (1$$\ 	ext{mole} = 6.02 	imes $$10^{23}$$ molecules)

Accepted Answer

$$\frac{3.0 	imes 10$$^{24}$$}{6.02 	imes 10$$^{23}$$} = 4.98$$ moles

Fundamental Concepts in GOB Chemistry: Atomic Structure, Periodic Table, and Chemical Calculations

Guida di studio - Domande di pratica

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