Q: Which orbital-filling diagram represents the ground state of oxygen?

$$[\text{He}]\ \uparrow\downarrow\ 2s\ \uparrow\ 2p_x\ \uparrow\ 2p_y\ \uparrow\downarrow\ 2p_z$$

Question 1

A solution contains 0.736 M KBr. What volume of this solution is needed to provide 303.6 g of KBr? (Molar mass of KBr = 119.0 g/mol)

Accepted Answer

$$2.12\ 	ext{L}$$

Question 2

How many electrons are in the ion $$	ext{PO}_4$$^{3-}$$?

Accepted Answer

$$50$$

Question 3

Using the VSEPR model, what is the molecular geometry of the central atom in $$	ext{BF}_3$$?

Accepted Answer

Trigonal planar

Question 4

Which of the following molecules has the weakest bonds?

Accepted Answer

$$	ext{Cl}_2$$

Question 5

How many electrons are in the outermost shell of the $$	ext{Ca}^{2+}$$ ion in its ground state?

Accepted Answer

$$0$$

Question 6

Which of the following pairs have the same number of valence electrons?

Accepted Answer

$$	ext{Li}$$, $$	ext{Na}$$

Question 7

A mixture of Xe, Kr, and Ar has a total pressure of 670 atm. What is the mole fraction of Kr if the partial pressures of Xe and Ar are 140 atm and 280 atm, respectively?

Accepted Answer

$$0.373$$

Question 8

A solution of LiCl in water is 0.27 M. What is the mole fraction of LiCl?

Accepted Answer

$$0.0048$$

Question 9

Calculate the work energy, $$w$$, gained or lost by the system when a gas expands from 15.1 L to 35.1 L against a constant external pressure of 1.5 atm. $$[1\ 	ext{L} \cdot 	ext{atm} = 101\ 	ext{J}]$$

Accepted Answer

$$-3.03\ 	ext{kJ}$$

Question 10

What is the molar concentration of sodium ions in a $$0.450\ 	ext{M}$$ $$	ext{Na}_3	ext{PO}_4$$ solution?

Accepted Answer

$$1.35\ 	ext{M}$$

Question 11

A solution is 2.25% by weight $$	ext{NaHCO}_3. $$How many grams of $$	ext{NaHCO}_3$$ are in 150.0 g of solution?

Accepted Answer

$$3.38\ 	ext{g}$$

Question 12

Which orbital-filling diagram represents the ground state of oxygen?

Accepted Answer

$$[	ext{He}]\ \uparrow\downarrow\ 2s\ \uparrow\ 2p_x\ \uparrow\ 2p_y\ \uparrow\downarrow\ 2p_z$$

Question 13

The pressure exerted by 15.0 mL of gas in a 3.1 L flask at 22°C is ______ kPa.

Accepted Answer

$$19.0$$

Question 14

A gas originally at 27°C and 1.00 atm pressure in a 3.91 L flask is cooled at constant pressure until the temperature is 11°C. The new volume of the gas is ______.

Accepted Answer

$$3.70\ 	ext{L}$$

Question 15

Which compound has the highest boiling point?

Accepted Answer

$$	ext{HF}$$

Question 16

At 298 K the average kinetic energy is the same for He, H$$_2$$, and N$$_2. $$The gas with the highest average velocity is ______.

Accepted Answer

$$	ext{He}$$

Question 17

How many of the following molecules are polar? $$	ext{XeCl}_2$$, $$	ext{CO}_2$$, $$	ext{PCl}_3$$, $$	ext{SF}_4$$

Accepted Answer

$$3$$

Question 18

A balloon contains 0.76 mol N$$_2$$, 0.18 mol O$$_2$$, 0.031 mol He and 0.026 mol H$$_2 at 770 mm Hg. $$What is the partial pressure of O$$_2$$?

Accepted Answer

$$130\ 	ext{mm Hg}$$

Question 19

What type of bonding is found in the compound OF$$_2$$?

Accepted Answer

Covalent bonding

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