Chemistry Quiz

What is the oxidation state of molybdenum in the ion MoO₄^2-?

• A) +4

• B) +6

• C) +2

• D) +8

The half-life of the radioactive isotope oxygen-15 is 2 minutes

• A) 5 minutes

• B) 2 minutes

• C) 10 minutes

• D) 1 minute

Which nuclide is produced when one atom of oxygen-15 decays by the emission of one positron?

• A) Nitrogen-15

• B) Oxygen-16

• C) Carbon-14

• D) Nitrogen-14

If a quantity of oxygen-15 decays by positron emission, what fraction of the original amount is left after 10 minutes?

• A) 1/16

• B) 1/4

• C) 1/8

• D) 1/2

Why is the second molar ionisation energy of sodium greater than its first molar ionisation energy?

• A) Removal of an electron from a more stable electron configuration

• B) Increased nuclear charge after the first ionisation

• C) Decreased distance between the nucleus and the electron cloud

• D) Decreased shielding effect of the inner electrons

What is the empirical formula of the explosive ADN based on its structural formula provided in the text?

• C2H6N4O4

• C2H4N4O2

• C2H6N6O4

• C2H6N4O2

What are the products formed when sodium hydrogen carbonate (NaHCO3) is heated according to the reaction provided?

• Na2CO3 and H2O

• Na2CO3, CO2, and H2O

• NaCO3 and CO2

• NaHCO3 and CO2

What is the expression for the equilibrium constant K_c for the reaction between hydrogen and iodine to form hydrogen iodide?

• K_c = [HI]^2/[H_2][I_2]

• K_c = [H_2][I_2]/[HI]^2

• K_c = [HI]/[H_2][I_2]

• K_c = [H_2][I_2]/[HI]

Given the equilibrium constant K_c = 46.0 for the reaction of hydrogen and iodine, the concentration of iodine I_2 is 1.20 mol dm^-3, and the concentration of hydrogen iodide HI is 15.00 mol dm^-3, calculate the concentration of hydrogen H_2.

What is the product formed when iron(III) oxide reacts with carbon monoxide?

• Iron and sulfur dioxide

• Iron and carbon dioxide

• Iron and oxygen

• Iron and water vapor