EST II HS Chemistry (2026) Mock Examination

A set of 60 practice flashcards covering atomic structure, bonding, gas laws, equilibrium, and general chemistry concepts from the Mock Examination.

Which element from the set (Sodium, Chlorine, Argon, Potassium) has the electron configuration [Ne]3s¹?

Sodium (Na, Z=11)

Which element from the set (Sodium, Chlorine, Argon, Potassium) is classified as a noble gas?

Argon (Ar, Z=18)

Which element from the set (Sodium, Chlorine, Argon, Potassium) forms a $-1$ ion most readily?

Chlorine (Cl, Z=17)

Which compound from the set ($NaCl$, $CH_4$, $H_2O$, $CO_2$) has primarily ionic bonding?

$$NaCl$$

Which compound from the set ($NaCl$, $CH_4$, $H_2O$, $CO_2$) exhibits hydrogen bonding between molecules?

$$H_2O$$

Which compound from the set ($NaCl$, $CH_4$, $H_2O$, $CO_2$) is described in the text as having nonpolar covalent bonds but a polar molecule?

None of the provided options ($NaCl$, $CH_4$, $H_2O$, $CO_2$) accurately fit this description based on standard electronegativity.

According to the Arrhenius theory, what is a substance that produces $H^+$ ions in aqueous solution?

Arrhenius acid

Under the Brønsted-Lowry theory, how is a proton donor defined?

Brønsted-Lowry acid

Under the Brønsted-Lowry theory, how is a proton acceptor defined?

Brønsted-Lowry base

Which gas law states that $V \propto n$ at constant temperature and pressure?

Avogadro's Law

Which gas law states that $P \propto T$ at constant volume and amount?

Gay-Lussac's Law

Which gas law states that $V \propto T$ at constant pressure and amount?

Charles's Law

In the equilibrium system $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \Delta H = -92\,kJ$, what happens if the temperature is increased?

The system shifts to the left (favors reactants).

In the equilibrium system $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \Delta H = -92\,kJ$, what happens if the pressure is increased?

The system shifts to the right (favors products).

In the equilibrium system $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \Delta H = -92\,kJ$, what is the effect of adding a catalyst?

There is no shift in equilibrium.

Which quantum number describes the shape of an orbital?

Angular momentum quantum number ($l$)

What does the Pauli exclusion principle state regarding electrons in an atom?

No two electrons in an atom can have the same four quantum numbers ($n$, $l$, $m_l$, $m_s$).

What is the VSEPR molecular shape of $SF_4$?

See-saw

According to the Pauling scale, which element has the highest electronegativity?

Fluorine (F)

What is the intermolecular force present in all molecules due to temporary dipoles?

London dispersion forces

Which group of elements on the periodic table (excluding Hydrogen) are known as alkali metals?

Group 1 (Li, Na, K, Rb, Cs, Fr)

What is the correct chemical name for $Fe_2O_3$?

Iron(III) oxide

Under what conditions would a polar covalent bond form between two atoms?

When there is a difference in electronegativity between two different nonmetals ($\Delta EN$ between $0.4$ and $1.7$).

What is the molecular geometry of a molecule with 3 bonding pairs and 1 lone pair of electrons?

Trigonal pyramidal

Which physical property decreases as you move down Group 1 (alkali metals)?

Ionization energy

What is the coefficient of $O_2$ when ethane ($C_2H_6$) is completely combusted into $CO_2$ and $H_2O$?

$7$ ($2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O$)

In the redox reaction $2Al + 3Cu^{2+} \rightarrow 2Al^{3+} + 3Cu$, which species undergoes oxidation?

$Al$ (Aluminum)

What is the $pH$ of a solution with a hydrochloric acid concentration of $0.001\,M$?

$3$ ($pH = -\log(10^{-3})$)

What mass of $NaOH$ is required to prepare $250\,mL$ of a $0.1\,M$ solution (Molar mass = $40\,g/mol$)?

$$1.0\,g$$

What is the empirical formula of a compound consisting of $40\%$ Carbon, $6.7\%$ Hydrogen, and $53.3\%$ Oxygen by mass?

$$CH_2O$$

In an electrochemical cell, at which electrode does oxidation occur?

Anode

Which metal (Mg, Zn, Cu, Fe) will NOT react with dilute $HCl$ because it is below Hydrogen in the activity series?

Copper (Cu)

What is the oxidation number of Chromium (Cr) in the dichromate ion ($Cr_2O_7^{2-}$)?

$$+6$$

If a titration uses $25.0\,mL$ of $0.100\,M$ $NaOH$ to neutralize $20.0\,mL$ of $H_2SO_4$, what is the molarity of the acid?

$$0.0625\,M$$

When $2\,mol$ of $H_2$ reacts with $1\,mol$ of $O_2$ to form water, which substance is the limiting reactant?

Neither (it is an exact stoichiometric match)

Which gas law states that at constant temperature, the volume of a gas is inversely proportional to its pressure ($P_1V_1 = P_2V_2$)?

Boyle's Law

According to Raoult's Law, what happens to the vapor pressure of a solvent when a nonvolatile solute is added?

The vapor pressure is lower than that of the pure solvent.

What is the molarity of a solution made by dissolving $5.85\,g$ of $NaCl$ ($58.5\,g/mol$) in $250\,mL$ of water?

$$0.4\,M$$

According to Graham's Law, which gas will effuse faster: $CO_2$, $O_2$, $N_2$, or $CH_4$?

$CH_4$ (Molar mass = $16\,g/mol$)

What is the boiling point of a $0.5\,m$ $NaCl$ solution if the boiling point elevation constant for water is $0.512\,^{\circ}C/m$?

$100.512\,^{\circ}C$ ($\Delta T_b = 2 \times 0.512 \times 0.5 = 0.512$)

What factor is the solubility of a gas proportional to according to Henry's Law?

Partial pressure of the gas above the solution

What volume does $1\,mole$ of any ideal gas occupy at Standard Temperature and Pressure (STP)?

$$22.4\,L$$

What do colligative properties depend on?

The number of solute particles (concentration) rather than the nature/identity of the solute.

What is the mathematical equation for the Ideal Gas Law?

$$PV = nRT$$

How does the solubility of most solids in water change as temperature increases?

Solubility increases with increasing temperature.

What three requirements must be met for a reaction to occur according to collision theory?

Molecules must collide, have sufficient energy (activation energy), and have proper orientation.

Which value describes the position of a reaction but does NOT affect the reaction rate?

Equilibrium constant ($K$)

In the reaction $N_2 + 3H_2 \rightleftharpoons 2NH_3$, if the concentration of $NH_3$ is doubled, how does the reaction quotient $Q$ change relative to $K$?

$Q$ becomes $4K$

How does a catalyst increase the rate of a chemical reaction?

It decreases the activation energy ($E_a$) by providing an alternative pathway.

For an exothermic reaction ($\Delta H$ is negative), what is the effect of increasing the temperature?

It favors the reactants (shifts the equilibrium to the left).

What are the units for a second-order rate constant?

$$M^{-1}s^{-1}$$

What define the state of dynamic equilibrium in a reversible reaction?

The forward rate equals the reverse rate, and the concentrations of reactants and products remain constant.

If Q < K, in which direction will the reaction proceed?

Forward (towards the products)

Which equation relates the rate constant of a reaction to its temperature and activation energy?

Arrhenius equation ($k = Ae^{-E_a/RT}$)

According to Le Châtelier's principle, what is the effect of decreasing volume on a reversible gas reaction?

The equilibrium shifts to the side with fewer moles of gas.

What is the safety rule for diluting strong acids?

Always add acid to water slowly to dissipate heat safely.

Which piece of laboratory glassware is the most precise for measuring volume?

Burette

In a chemical titration, what is the 'endpoint'?

The point at which the indicator changes color, near the equivalence point.

What is the formula for calculating percentage error?

$$\frac{|\text{measured} - \text{accepted}|}{\text{accepted}} \times 100\%$$

What essential PPE (Personal Protective Equipment) should be worn when handling chemicals?

Safety goggles, lab coat, and gloves