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
understand that chemical reactions are accompanied by enthalpy changes and these changes can be exothermic (\(\Delta H\) is negative) or endothermic (\(\Delta H\) is positive)
(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
define activation energy, \( E_A \), as the minimum energy required for a collision to be effective
