`I_(1)` of an element X is `899" kJ mole"^(-1)` and that of another element Y is `801" kJ mole"^(-1)`. Then X and Y may be

I_1 of an element X is 899 kJ "mole"^(-1) and that of another element Y is 801kJ mole-1. Then X and Y may be

When a mole of magnesium bromide is prepared from 1 mole of magnesium and 1 mole of liquid bromine, 524 kJ of energy is released. The heat of sublimation of Mg metal is 148 "kJ mol"^(-1) . The heat of dissociation of bromine gas into atoms is 193 "kJ mol"^(-1) . The heat of vaporization of liquid bromine is 31 kJ "mol"^(-1) . The ionisation energy of magnesium is 2187 kJ mol^(-1) and the electron affinity of bromine is - 662 "kJ mol"^(-1) . Calculate the lattice energy of magnesium bromide.

In an exothermic reaction X rarr Y , the activation energy is 100 kJ mol^(-1) of X . The enthalphy of the reaction is -140 kJ mol^(-1) . The activation energy of the reverse reaction Y rarr X is

In an exothermic reaction X rarr Y , the activation energy is 100 kJ mol^(-1) of X . The enthalphy of the reaction is -140 kJ mol^(-1) . The activation energy of the reverse reaction Y rarr X is

The reaction X to Y is an exothermic reaction. Activation energy of the reaction for X into Y is 150 kJ mol^(-1) . Enthalpy of reaction is 135 kJ "mol"^(-1) . Calculate the activation energy for the reverse reaction, Y to X in kJ mol^(-1) .

An element "X" has IP=1681 kJ/mole and EA=-333 kJ/mole then its electronegativity is