Question

SECTION 1: True (T) or False (F) 1. _____ When an electron emits energy in the form of light, it drops from a higher energy level to a lower energy level. 2. _____ When a white solid is dissolved in a beaker containing room-temperature water, the solution becomes hot. This is an example of an endothermic reaction. 3. _____ The Lewis structure of NO2 is an exception to the octet rule. 4. _____ For any form of visible light, the frequency is proportional to the energy. 5. _____ When sulfuric acid reacts with sodium hydroxide, the products are water and sodium sulfate. 6. _____ The ammonium ion has tetrahedral geometry. 7. _____ In the Paper Chromatography experiment, the retention factor measures the ratio of the distance that the ion moves to the distance that the elution solvent moves. . A 2.000 gram sample of copper oxide was analyzed and produced 1.776 grams of copper. Calculate the mass percent of copper and oxygen in the copper oxide from the experimental data. (6 points) __________ % Cu ___________ % O There are two possible formulas for copper oxide. Based on each formula calculate the mass percent of copper and oxygen in each. CuO ______________ % Cu ______________ % O Cu2O ______________ % Cu ______________ % O Was the sample copper (I) oxide or copper (II) oxide? In the vinegar titration experiment, the student does not fill the buret tip before titrating. How would this affect the molar concentration calculation of the acetic acid? A. No change B. The molarity would increase. C. The molarity would decease. D. The indicator would not work properly. Which of the following statements is incorrect? A. An acidic solution turns blue litmus paper red. B. A basic (or alkaline) solution turns red litmus paper blue. C. Phenolphthalein is pink in acidic solution but colorless in basic solution. D. Phenolphthalein is pink in basic solution but colorless in acidic solution.

Answer 1

1. True (T).

Because electron excited from ground state (lower energy state) to excited state (higher energy state) by absorbing energy and returns to lower energy state by emitting energy as light.

2. False (F)

Endothermic reaction is the one which absorb energy from the surrounding and exothermic reaction gives the energy to the surroundings. So, the solution becomes cool in endothermic reaction.

3. True (T)

Octet rule: Atoms contains 8 valence electrons.

In Lewis structure of NO₂, N has only 7 valence electrons.

4. True(T)

Energy (E) = Planck's constant (h) x frequency (v)

So, the energy and frequency are proportional to each other.