Practice Test 1 - High School Chemistry

20 questions. Answer them in any order, then submit to see your score and every explanation.

Sodium (Na) is in Group 1 and has electron configuration $1s^2\,2s^2\,2p^6\,3s^1$ . A small piece of sodium reacts vigorously with water and forms $\text{Na}^+$ in the process. How does sodium's atomic structure explain this chemical behavior?
Calcium carbonate (CaCO $_3$ ) reacts with vinegar (aqueous acetic acid) to release carbon dioxide gas. A student runs the reaction at room temperature using the same volume and concentration of vinegar each time. Trial 1 uses one large CaCO $_3$ chip; Trial 2 uses the same mass of CaCO $_3$ crushed into a powder. What is the expected effect on the reaction rate in Trial 2, based on collision theory?
Neon (Ne) has electron configuration $1s^2\,2s^2\,2p^6$ and is very unreactive under normal conditions. Which structural feature best explains neon's lack of reactivity?
A student observes that when steel wool rusts, its mass increases. In an experiment, dry steel wool has a mass of 30 g. After sitting in moist air for several days, the rusted steel wool has a mass of 38 g. Which explanation best fits the law of conservation of mass?
Iron reacts with chlorine to form iron(III) chloride: $\mathrm{2Fe + 3Cl_2 \rightarrow 2FeCl_3}$ Which statement correctly describes the mole relationship between iron ( $\mathrm{Fe}$ ) and chlorine gas ( $\mathrm{Cl_2}$ )?
Hydrogen reacts with oxygen in a sealed container: 2H $_2$ (g) + O $_2$ (g) → 2H $_2$ O(l). The container initially has 6 g of H $_2$ and 48 g of O $_2$ . Assuming the reaction goes to completion and nothing escapes, what total mass of products should be measured?
Ammonia forms by the reaction $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$ If $2.0\,\text{mol}$ of $\text{N}_2$ and $4.0\,\text{mol}$ of $\text{H}_2$ are available, which reactant is limiting?
A student compares the reactivity of halogens with metals. Consider fluorine (F, Group 17 Period 2), chlorine (Cl, Group 17 Period 3), and iodine (I, Group 17 Period 5). Which is expected to be the least reactive halogen based on periodic trends in Group 17?
Two processes both release energy: (1) combustion of methane on a stove (chemical) and (2) fusion in the Sun (nuclear). Which option correctly explains why fusion releases vastly more energy per reaction event than combustion?
A student adds a spoonful of sugar to warm water and stirs. The sugar disappears and the liquid remains clear; no bubbles form and no solid appears. Which observation is NOT evidence of a chemical reaction?
A neutral atom has 9 protons and a mass number of 19. How many neutrons and electrons does it have?
Hydrogen chloride forms by $\text{H}_2 + \text{Cl}_2 \rightarrow 2\text{HCl}.$ If 5.0 mol $\text{H}_2$ react with 2.0 mol $\text{Cl}_2$ , which reactant will be completely consumed first?
A beaker contains 100 mL of 1.0 M HCl at 25°C. A student adds a single 2.0 g piece of zinc to start the reaction that produces hydrogen gas. The student proposes stirring the solution continuously with a glass rod while keeping temperature, concentration, and zinc size the same. Assuming stirring mainly helps bring fresh acid into contact with the zinc surface, what is the best prediction about the reaction rate with stirring compared to without stirring?
Calcium carbonate decomposes according to $\text{CaCO}_3 \rightarrow \text{CaO} + \text{CO}_2.$ If $2.5\ \text{mol}$ of $\text{CaCO}_3$ decompose completely, how many moles of $\text{CO}_2$ are produced?
Two colorless liquids are mixed in a sealed container. - Liquid X: 20.0 mL, 18.0°C, mass = 19.6 g, colorless - Liquid Y: 20.0 mL, 18.0°C, mass = 19.8 g, colorless After mixing for 30 seconds (sealed container): - Total mass of container + contents: unchanged - Temperature: 18.0°C - Appearance: colorless and clear What does the data most strongly suggest?
Hydrogen peroxide breaks down faster in the presence of a catalyst such as manganese(IV) oxide: $2\text{H}_2\text{O}_2\text{(aq)} \rightarrow 2\text{H}_2\text{O(l)} + \text{O}_2\text{(g)}$ A student has 3% $\text{H}_2\text{O}_2$ at 25°C. They add a small amount of $\text{MnO}_2$ powder while keeping temperature and concentration the same. What happens to the reaction rate, and why?
Select the correctly balanced form of the reaction (smallest whole-number coefficients): AgNO3 + NaCl → AgCl + NaNO3
A reaction is exothermic overall. Which description of the bond-energy "balance" is correct for an exothermic reaction?
A science museum needs a material for a clear display box that will contain iodine crystals. Iodine produces purple vapor that can stain or react with some plastics. Requirements: the box should be transparent for viewing, should limit chemical reaction/staining over several months, and must be safe for visitors (no cracking/leaks). Budget is limited. Which option is the best trade-off? Options: - Acrylic (clear plastic): clear and inexpensive; can craze/stain with some chemicals over time. - Glass: clear and chemically resistant; heavier and breakable; moderate cost. - Polycarbonate: very impact-resistant and clear; more expensive; can still show some chemical stress with certain vapors.
A student places a clean iron nail into a cup of blue liquid. After several minutes, the blue color fades noticeably, and a reddish-brown coating appears on the nail. Which observation is the clearest evidence that a chemical reaction occurred?

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