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The atomic mass of bromine is 79.904. Given that the only two naturally occurring isotopes are 79 Br and 81 Br, the abundance of  79 Br isotope is approximately:

(A) 20 percent

(B) 40 percent

(C) 50 percent

(D) 80 percent

(E) 99 percent

What volume of distilled water should be added to 20 mL of 5 M HCl (aq) to prepare a 0.8-M

solution?

(A) 100 mL

(B) 105 mL

(C) 125 mL

(D) 140 mL

(E) 200 mL

How many molecules are contained in 180 g of water (H 2 O)?

(A) 6.02 × 10^22

(B) 1.20 × 10^23

(C) 6.02 × 10^23

(D) 1.20 × 10^24

(E) 6.02 × 10^24

How many oxygen atoms are in 4.4 g of CO 2 ?

(A) 6.02 × 10^22

(B) 1.20 × 10^23

(C) 1.20 × 10^24

(D) 6.02 × 10^23

(E) 6.02 × 10^24

Which of the following chemical equations represents the intense heating of solid hydrogen carbonate (sodium bicarbonate)?

(A) NaHCO 3 → Na+ H 2 O + CO 2

(B) NaHCO 3 → Na 2 CO 3 + H 2 O + CO 2

(C) NaHCO 3 → Na+ H 2 + O 2 + CO 2

(D) Na(CO 3 ) 2 → Na + Na 2 CO 3 + H 2 O + CO 2

(E) Na(CO 3 ) 2 → Na 2 CO 3 + H 2 O + CO 2

Questions6-9  refer to the following answer choices:

(A) MgO + CO 2 → MgCO 3

(B) I ? + Cd 2+ → CdI 4 2–

(C) SiH 4 + O 2 → SiO 2 + H 2 O

(D) CaO + SO 2 → CaSO 3

(E) Mg (s) → Mg 2+ + 2 e ?

6. A combustion reaction

7. A reaction that produces a complex ion

8. An oxidation that is not a combustion

9. A reaction in which the product forms a gas in acidic solutions

Which of the following is the correct net ionic equation for the reaction of sodium hydroxide and nitric acid?

(A) H + + OH ? → H 2 O

(B) Na + + NO 3 ? → NaNO 3

(C) NaOH + HNO 3 → NaNO 3 + H 2 O

(D) Na + + OH ? + H + + NO 3 ? → NaNO 3 + H 2 O

(E) Na + + OH ? + 2 H + → NaOH + H 2

Questions 11-15 refer to aqueous solutions containing 1:1 mole ratios of the following pairs of substances. Assume all concentrations are 1 M.

(A) NH 3 and H 3 CCOOH (acetic acid)

(B) KOH and NH 3

(C) HCl and KCl

(D) H 3 PO 4 and KH 2 PO 4

(E) NH 3 and NH 4 Cl

11. The solution with the highest pH

12. The solution with the lowest pH

13. The solution with the pH closest to neutral

14. A buffer at an alkaline pH

15. A buffer at an acidic pH

The oxidation state of chlorine in HClO 4 is:

(A) –1

(B) +1

(C) +3

(D) +5

(E) +7

The oxidation state most common to ions of Fe, Mn, and Zn in solution is:

(A) +1

(B) +2

(C) +3

(D) +4

(E) +5

A student accidentally splashes a concentrated, strong acid onto his bare skin. Which of the following is the safest and most effective course of action?

(A) Dry the skin with paper towels.

(B) Flush the area with water and a dilute solution of a weak acid.

(C) Flush the area with a dilute NaOH solution, then water.

(D) Flush the area with water and then a dilute solution of NaHCO 3 .

(E) Sprinkle the area with powdered Na 2 SO 4 , then carefully shake off the excess and rinse with water

Which equation for the reaction between sodium carbonate and dilute hydrochloric acid is correct?

A  Na 2 CO 3 (s) + HCl (aq) → NaCl (aq) + CO 2 (g) + H 2 O(I)

B  Na 2 CO 3 (s) + HCl (aq) → Na 2 Cl (aq) + CO 2 (g) + H 2 O(I)

C  Na 2 CO 3 (s) + 2HCl (aq) → NaCl (aq) + CO 2 (g) + H 2 O(I)

D  Na 2 CO 3 (s) + 2HCl (aq) → 2NaCl (aq) + CO 2 (g) + H 2 O(I)

Which statement about bonding is not correct?

A  Carbon can form four single covalent bonds.

B  Chlorine atoms react to gain a noble gas electronic structure.

C  Covalent bonding involves losing and gaining electrons.

D  Hydrogen molecules have the formula H 2

The diagram shows the apparatus used to separate a mixture of water, boiling point 100 °C, and  ethanol, boiling point 78 °C.

(a) Complete the boxes to name the apparatus.  [2]

(b) Label the arrows on the condenser.  [1]

(c) Identify one mistake in the apparatus.

............................................................. [1]

(d) Which liquid would collect first? Explain your answer.

................................................................[2]

(e) Why would it be better to use an electrical heater instead of a Bunsen burner to heat the water and ethanol mixture?

.........................................................[1]

[Total: 8]

Air is a mixture of gases. The diagram shows the apparatus used to find the percentage of oxygen in air.

50 ml of air were passed backwards and forwards over excess heated copper until there was no further change. The apparatus was left to cool and the volume of gas remaining was 40 ml .

(a) Complete the box to name the apparatus.  [1]

(b) Use an arrow to indicate where heat is applied.  [1]

(c)The colour of the copper changed from ........................... to ........................... .  [2]

(d) From the results, work out the percentage of oxygen in the air.

............................ % [2]

[Total: 6]

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