Q: If the pH of a solution is 2.50, what is the concentration of OH$$^- in $$the solution? ($$K_w = 1.0 \times 10$$^{-14}$$)

$$[\mathrm{OH}^-] = 3.16 \times 10$$^{-12}$$

Question 1

Which of the following statements is TRUE regarding the ionization of strong acids in aqueous solution?

Accepted Answer

Strong acids are 100\% ionized in water.

Question 2

A solution is prepared by mixing 40.0 mL of 0.10 M HCl and 60.0 mL of 0.20 M $$HNO_3. $$What is the pH of the resulting solution? (Assume volumes are additive and both acids are strong.)

Accepted Answer

The pH is 0.82

Question 3

Arrange the following oxyacids in order of increasing acid strength: HClO, $$HClO_2$$, $$HClO_3.$$

Accepted Answer

HClO \u003c $$HClO_2$$ \u003c $$HClO_3$$

Question 4

A buffer is prepared by mixing 0.400 M acetic acid (CH_3COOH) and 0.500 M sodium acetate (NaCH_3COO). If the $$K_a of $$acetic acid is $$1.8 	imes 10$$^{-5}$$, what is the pH of the buffer?

Accepted Answer

The pH is 4.89

Question 5

Which of the following combinations will produce a buffer solution when mixed in water?

Accepted Answer

$$NH_3$$ and NH_4Cl

Question 6

A 100-mL sample of saturated Ca(OH)_2 solution is titrated with 0.500 M HCl. If it takes 40.0 mL of the acid to reach the endpoint, what is the concentration of Ca(OH)_2 in the original solution?

Accepted Answer

0.100 M

Question 7

Consider the following exothermic reaction at equilibrium: $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}. If $$the temperature is increased, what will happen to the position of equilibrium and the value of $$K$$?

Accepted Answer

The reaction will shift toward the reactants and $$K$$ will decrease.

Question 8

When phosphorus-32 ($$^{32}_{15}P) $$decays by beta emission, what is the product nucleus?

Accepted Answer

$$^{32}_{16}S$$

Question 9

Curium-248 ($$^{248}_{96}Cm) $$undergoes alpha decay. What is the identity of the daughter nucleus?

Accepted Answer

$$^{244}_{94}Pu$$

Question 10

A buffer solution contains 1.00 M CH_3COOH and 1.00 M CH_3COONa. If a small amount of NaOH is added, what will happen to the concentrations of CH_3COOH and CH_3COONa?

Accepted Answer

CH_3COOH will decrease and CH_3COONa will increase.

Question 11

In the following reaction, identify the Bronsted-Lowry base on the left side: $$\mathrm{$$HCO_3$$^- (aq) + H_2O (l) \rightleftharpoons H_2CO_3 (aq) + OH^- (aq)}$$

Accepted Answer

$$HCO_3^- (aq)$$

Question 12

If the pH of a solution is 2.50, what is the concentration of OH$$^- in $$the solution? ($$K_w = 1.0 	imes 10$$^{-14}$$)

Accepted Answer

$$[\mathrm{OH}^-] = 3.16 	imes 10$$^{-12}$$

Question 13

What happens to the atomic number and mass number of an atom when it undergoes alpha decay?

Accepted Answer

The atomic number decreases by 2 and the mass number decreases by 4.

Question 14

How many protons, neutrons, and electrons are present in an atom of $$^{131}_{53}I$$?

Accepted Answer

53 protons, 78 neutrons, 53 electrons

Question 15

The half-life of a radioactive isotope is 3.0 days. If a sample contains 80.0 mg initially, how much remains after 9.0 days?

Accepted Answer

10.0 mg

Question 16

A patient is to receive 250 μCi/kg of a radioisotope. If the patient weighs 70 kg and the solution contains 10.0 mCi/mL, what volume should be administered?

Accepted Answer

1.75 mL

Question 17

Why is it important for radioisotopes used in medical imaging to have short half-lives?

Accepted Answer

Short half-lives minimize the harmful side effects of radiation.

Question 18

What is the main scientific challenge in achieving controlled nuclear fusion for energy production?

Accepted Answer

Enormous repulsion between nuclei being fused.

Question 19

Which of the following statements is TRUE about nuclear fission?

Accepted Answer

Large amounts of energy are released when a nuclear reaction occurs.

Question 20

Which of the following salts will produce an acidic solution when dissolved in water?

Accepted Answer

NH_4Cl

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