Chemistry Quiz

Element X has six more protons than element Y. Which statement must be correct?

• Atoms of element Y are smaller than atoms of element X.

• Element X has a full shell of electrons.

• Element X and element Y are in the same group.

• Element X and element Y are in the same period.

Which statement explains why calcium has a higher melting point than barium?

• Calcium cations are smaller than barium cations and have a stronger attraction to the delocalised electrons.

• The structure of calcium is partly giant molecular.

• There are more delocalised electrons in calcium than in barium as it has a lower ionisation energy.

• There is greater repulsion between barium atoms as they have more complete electron shells than calcium atoms.

Three statements about potassium and chlorine and their ions are listed. Which statements are correct?

• The atomic radius of a potassium atom is greater than the atomic radius of a chlorine atom.

• The first ionisation energy of potassium is greater than the first ionisation energy of chlorine.

• The ionic radius of a potassium ion is greater than the ionic radius of a chloride ion.

For which equilibrium do both of the equilibrium constants Kc and Kp have no units?

• H2(g) + I2(g) → 2HI(g)

• N2(g) + 3H2(g) → 2NH3(g)

• N2O4(g) → 2NO2(g)

• SO2(g) + O2(g) → SO3(g)

What is the standard enthalpy change of the reaction shown?

In the sodium chloride lattice the number of chloride ions that surround each sodium ion is called the coordination number of the sodium ions. What are the coordination numbers of the sodium ions and the chloride ions in the sodium chloride lattice?

Histidine is an amino acid. What are the approximate bond angles 1, 2, and 3?

• 90°107°109.5°

• 109.5°107°120°

• 90°120°120°

The Contact process takes place at a pressure between 100000Pa and 200000Pa. A catalyst is used. Which statement is correct?

• V2O5 catalyst is added to increase the equilibrium yield of the reaction.

• Changes in pressure have no effect on the position of equilibrium.

• The equilibrium yield of the reaction is very high under the conditions used.

• An iron catalyst is added to increase the rate of reaction.

Bromine reacts with aqueous sodium hydroxide at 25°C. Which reactions are disproportionations?

Which statement is correct?

• The relative atomic mass of a 35Cl atom is 35.5.

• The relative formula mass of CaCO3 is 100.1.

• The relative isotopic mass of a 24Mg atom is 24.3.

• The relative molecular mass of O2 is 16.0.