$A$ $10 \ g$ piece of iron $(C = 0.45 \ J/g \ ^oC)$ at $100 \ ^oC$ is dropped into $25 \ g$ of water $(C = 4.2 \ J/g \ ^oC)$ at $27 \ ^oC$. Find the temperature of the iron and water system at thermal equilibrium in $^oC$.

Calculate $\Delta H^{\circ}$ for the reaction, $Na_2O_{(s)} + SO_{3(g)} \longrightarrow Na_2SO_{4(s)}$, given the following reactions:
$(A) \ Na_{(s)} + H_2O_{(l)} \longrightarrow NaOH_{(s)} + \frac{1}{2}H_{2(g)} \quad \Delta H^{\circ} = -146 \ kJ$
$(B) \ Na_2SO_{4(s)} + H_2O_{(l)} \longrightarrow 2NaOH_{(s)} + SO_{3(g)} \quad \Delta H^{\circ} = +418 \ kJ$
$(C) \ 2Na_2O_{(s)} + 2H_{2(g)} \longrightarrow 4Na_{(s)} + 2H_2O_{(l)} \quad \Delta H^{\circ} = +259 \ kJ$

The difference between enthalpy change and internal energy change for the combustion of one mole of ethyl alcohol is

The molar enthalpy change for $H_2O_{(l)} \rightleftharpoons H_2O_{(g)}$ at $373 \ K$ and $1 \ atm$ is $41 \ kJ \ mol^{-1}$. Assuming ideal behavior,the internal energy change for vaporization of $1 \ mol$ of water at $373 \ K$ and $1 \ atm$ in $kJ \ mol^{-1}$ is:

$A$ cylinder of gas supplied by Bharat Petroleum is assumed to contain $14 \ kg$ of butane. If a normal family requires $20,000 \ kJ$ of energy per day for cooking,how many days will the butane gas in the cylinder last? ($\Delta H_c$ of $C_4H_{10} = -2658 \ kJ/mole$)

Identify the incorrect statements among the following:
$(a)$ All enthalpies of fusion are positive.
$(b)$ The magnitude of enthalpy change does not depend on the strength of the intermolecular interactions in the substance undergoing phase transformations.
$(c)$ When a chemical reaction is reversed,the value of $\Delta_r H^{\circ}$ is reversed in sign.
$(d)$ The change in enthalpy is dependent on the path between the initial state (reactants) and final state (products).
$(e)$ For most of the ionic compounds,$\Delta_{\text{sol}} H^{\circ}$ is negative.