Q: How many molecules are present in 163 g of $$CO_2$$? (Molar mass of $$CO_2 = 44.0$ g/mol, Avogadro's number = 6.02$$ \times $$10^{23})$$

$$2.23 \times 10$$^{24}$$ molecules

Q: Which of the following is the correct calculation for the number of atoms in 5.29 g of carbon? (Molar mass of C = 12 g/mol, Avogadro's number $$= 6.02 \times 10$$^{23}$$)

$$\frac{5.29}{12} \times 6.02 \times 10$$^{23}$$

Question 1

Which of the following best describes the process of photosynthesis in the carbon cycle?

Accepted Answer

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6$ + 6O_2$$

Question 2

A sample of silicon contains three isotopes: $$^{28}Si (27.9769 $$amu, 92.21%), $$^{29}Si (28.9766 $$amu, 4.70%), and $$^{30}Si (29.9738 $$amu, 3.09%). What is the average atomic mass of silicon?

Accepted Answer

$$28.09$$ amu

Question 3

Which of the following statements about greenhouse gases is correct?

Accepted Answer

Greenhouse gases must have three or more atoms to absorb infrared radiation.

Question 4

How many molecules are present in 163 g of $$CO_2$$? (Molar mass of $$CO_2 = 44.0$ g/mol, Avogadro's number = 6.02$$ 	imes $$10^{23})$$

Accepted Answer

$$2.23 	imes 10$$^{24}$$ molecules

Question 5

Which of the following best explains why $$CO_2 is a $$greenhouse gas but $$N_2 is $$not?

Accepted Answer

$$CO_2$$ has a molecular shape and vibrations that allow it to absorb IR radiation, while $$N_2$$ does not have a dipole moment during vibration.

Question 6

A 48.7 g sample of potassium ($$K) $$contains how many moles? (Molar mass of $$K = 39 g/$$mol)

Accepted Answer

$$1.25$$ moles

Question 7

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

Accepted Answer

$$Al_2$$($$SO_4)_3$

Question 8

What is the molecular geometry and bond angle of $$CH_4$$ according to VSEPR theory?

Accepted Answer

Tetrahedral, $$109.5^\circ$$

Question 9

Which of the following is a correct description of the greenhouse effect?

Accepted Answer

It is a natural process where atmospheric gases absorb and emit infrared radiation, warming the atmosphere.

Question 10

Which of the following ions is a polyatomic ion?

Accepted Answer

$$SO_4$$^{2-}$$

Question 11

A sample contains $$3.80 	imes 10$$^{22}$$ atoms of krypton (Kr$). What is the mass of this sample? (Molar mass of Kr = 83.80$ g/mol, Avogadro's number = 6.02$$ 	imes $$10^{23})$$

Accepted Answer

$$5.29 g$$

Question 12

Which of the following best describes the formation of an ionic compound?

Accepted Answer

A metal loses electrons to form a cation and a nonmetal gains electrons to form an anion; the oppositely charged ions attract.

Question 13

Which of the following is the correct name for $$Fe_2O_3$$?

Accepted Answer

Iron(III) oxide

Question 14

How many moles of oxygen atoms are present in 25.0 g of $$NO_2$$? (Molar mass of $$NO_2 = 46.0$ g/mol)

Accepted Answer

$$1.09$$ moles

Question 15

Which of the following is a major impact of climate change as discussed in the study materials?

Accepted Answer

Sea level rise

Question 16

Which of the following best explains why ionic compounds shatter when struck with a hammer?

Accepted Answer

The rigid lattice of oppositely charged ions is disrupted, causing like charges to repel and the crystal to break.

Question 17

Which of the following is the correct electron group geometry and molecular shape for $$H_2O$$ according to VSEPR theory?

Accepted Answer

Tetrahedral electron group geometry, bent molecular shape

Question 18

Which of the following best describes how ice core data is used to study past climate change?

Accepted Answer

By analyzing air bubbles trapped in ice layers to determine past concentrations of greenhouse gases and temperature proxies.

Question 19

Which of the following is the correct calculation for the number of atoms in 5.29 g of carbon? (Molar mass of C = 12 g/mol, Avogadro's number $$= 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$\frac{5.29}{12} 	imes 6.02 	imes 10$$^{23}$$

General Chemistry CHM110: Climate Change, Atomic Mass, and Mole Concepts

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