Q: How many water molecules are present in 2.50 mol of $$H_2O$$? Use Avogadro's number $$6.022 \times 10$$^{23}$$ molecules/mol.

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

Question 1

How many water molecules are present in 2.50 mol of $$H_2O$$? Use Avogadro's number $$6.022 	imes 10$$^{23}$$ molecules/mol.

Accepted Answer

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

Question 2

Which molecule has the largest molar mass?

Accepted Answer

$$C_3H_8O_3$$

Question 3

A patient is prescribed 40 mg of Solu-Medrol per dose. If the available solution contains 12.5 mg per 2 mL, how many mL should be administered per dose?

Accepted Answer

6.4 mL/dose

Question 4

How many moles of uric acid are in 281.7 g of uric acid? (Molar mass = 168.11 g/mol)

Accepted Answer

1.68 mol

Question 5

Given the reaction $$3NO_2(g) + H_2O(g) \rightarrow 2HNO_3(g) + NO(g)$$, how many moles of $$H_2O$$ are required to react completely with 6 moles of $$NO_2$$?

Accepted Answer

2 moles

Question 6

How many grams of $$H_2O$$ are required to react completely with 3.0 moles of $$NO_2$$? ($$H_2O$$ molar mass = 18.02 g/mol)

Accepted Answer

18 g

Question 7

How many moles of NaCl are in 3.75 L of a 0.485 M solution?

Accepted Answer

1.82 mol

Question 8

Which compound acts as a base when dissolved in water?

Accepted Answer

$$Ca(OH)_2$$

Question 9

A sample of lake water has a pH of 6.3. Which description best characterizes this sample?

Accepted Answer

slightly acidic

Question 10

Which reaction is NOT an acid-base neutralization?

Accepted Answer

$$BaCl_2(aq) + Na_2SO_4(aq$$) \rightarrow $$BaSO_4(s) + 2$$NaCl(aq)$$

Question 11

How many moles of $$HCl$$ are required to completely neutralize 1.85 moles of $$Mg(OH)_2$$? Use the reaction: $$2HCl(aq) + Mg(OH)_2(aq) \rightarrow 2H_2O(l) + $$MgCl_2$$(aq).$$

Accepted Answer

3.70 mol

Question 12

If 16.2 mL of a 0.125 M $$HNO_3$$ solution is required to completely neutralize 10.5 mL of a NaOH solution, what is the concentration of the NaOH?

Accepted Answer

0.193 M

Question 13

Which chemical equation correctly represents the synthesis of methanol ($$CH_3OH) $$based on the equilibrium expression $$K = \frac{[CH_3OH]}{[CO][H_2$]^2}$$?

Accepted Answer

$$CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)$$

Question 14

Two sealed containers (1.25 L each at 95°C) contain 2.75 g of He and 2.75 g of Ar, respectively. Which statement is correct?

Accepted Answer

The flask containing helium has a higher pressure than the flask containing argon.

Question 15

Which is the most polar covalent bond?

Accepted Answer

$$C-O$$

Question 16

Classify the molecules shown in the first image as polar or nonpolar.

Accepted Answer

The left molecule ($$PBr_3) is $$polar; the right molecule (formaldehyde) is polar.

Question 17

What is the most important type of intermolecular force between the side chain of serine and water, as shown in the second image?

Accepted Answer

hydrogen bonds

Question 18

Name the molecular compound $$BF_3.$$

Accepted Answer

boron trifluoride

Question 19

Gold-198 decays by beta emission with a half-life of 2.7 days. How many days is three half-lives?

Accepted Answer

8.1 d

Question 20

Which pair of atoms is most likely to form a covalent bond?

Accepted Answer

C and O

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