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Class 9Class 10First YearSecond Year
$Q.19 Graphite and diamond are two forms of carbon. The enthalpy of combustion of graphite at 25^{\circ} \mathrm{C} is -393.51 \mathrm{~kJ} mol-1 and that of diamond is -395.41 \mathrm{~kJ} \mathrm{~mol}^{-1} . What is the enthalpy change of the process? Graphite \rightarrow Diamond at the same temperature? \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \rightarrow \mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g}) (Ans: 1.91 \mathrm{~kJ} \mathrm{~mol}^{-1} )$

$Q.5(a) Differentiate between the following:(i) Internal energy and enthalpy$

$Q.4. Define the following terms and give three examples of each(v) Exothermic reaction$

$Q.4. Define the following terms and give three examples of each(viii) Enthalpy of the system$

$(b) How do you measure the heat of combustion of a substance by bomb calorimeter.$

$Q.4. Define the following terms and give three examples of each(ii) Surroundings$

$Q.20 What is the meaning of the term enthalpy of ionization? If the heat of neutralization of \mathrm{HCl} and \mathrm{NaOH} is -57.3 \mathrm{~kJ} \mathrm{~mol}^{-1} and heat of neutralization of \mathrm{CH}_{3} \mathrm{COOH} with \mathrm{NaOH} is -55.2 \mathrm{~kJ} \mathrm{~mol}^{-1} calculate the enthalpy of ionization of \mathrm{CH}_{3} \mathrm{COOH} .(Ans: 2.1 \mathrm{~kJ} \mathrm{~mol}^{-1} )$