Older MCQs might not have the typical A, B, C,
D
choices. They
have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such
combinations to the answer.
A
1, 2 and 3 are correct
B
1 and 2 only are correct
C
2 and 3 only are correct
D
1 only is correct
(a) define the terms: - bond energy as the energy required to break one mole of a particular covalent bond in the gaseous state - bond length as the internuclear distance of two covalently bonded atoms (b) use bond energy values and the concept of bond length to compare the reactivity of covalent molecules
describe the relative thermal stabilities of the hydrogen halides and explain these in terms of bond strengths
describe, in simple terms, the lattice structure of a crystalline solid which is: (a) giant ionic, including sodium chloride and magnesium oxide (b) simple molecular, including iodine, buckminsterfullerene \( C_{60} \) and ice (c) giant molecular, including silicon(IV) oxide, graphite and diamond (d) giant metallic, including copper
