Round off the following measurement to three significant digits: 3255 mL. (a) 325 mL (b) 326 mL (c) 3250 mL (D) 3260 mL (e) none of the above

Explanation:

Let's analyze the statements one by one:

a) This process is exothermic.

True. The negative enthalpy change (-2,021 kJ) indicates that heat is released during the reaction, making it exothermic.

b) The enthalpy change for 2C₃H₇OH(l)+9O₂(g)→6CO₂(g)+8H₂O(l) is 2,021 kJ.

False. The balanced chemical equation and enthalpy change given are for the combustion of 1 mole of propanol, not 2 moles.

c) The enthalpy change for 2C₃H₇OH(l)+9O₂(g)→6CO₂(g)+8H₂O(l) is -4,042 kJ.

False. This statement suggests a doubled enthalpy change value in the wrong direction. The correct direction is negative (exothermic), but the magnitude is not doubled.

d) The enthalpy change for 2C₃H₇OH(l)+9O₂(g)→6CO₂(g)+8H₂O(l) is -2,021 kJ.

False. This statement suggests the correct direction but doubles the magnitude. The correct magnitude is -2,021 kJ for 1 mole of propanol.

e) This chemical process transfers heat from the surroundings to the system.

False. The process is exothermic, which means it releases heat from the system to the surroundings.

f) The enthalpy change for 2C₃H₇OH(l)+9O₂(g)→6CO₂(g)+8H₂O(l) is 4,042 kJ.

False. This statement suggests the correct magnitude but in the wrong direction. The correct direction is negative (exothermic).

g) This process is endothermic.

False. The process is exothermic, as indicated by the negative enthalpy change.

h) This chemical process transfers heat from the system to the surroundings.

True. An exothermic process like this releases heat from the system to the surroundings.

So, the correct statements are:

a) This process is exothermic.

e) This chemical process transfers heat from the surroundings to the system.

h) This chemical process transfers heat from the system to the surroundings.

Answer:

             Option-D (Compounds with different boiling point)

Explanation:

                    Compound is defined as a molecule which is made up of two or more different elements. All compounds are molecules but all molecules are not compounds, for example N₂, O₂, S₈, H₂, F₂ etc are molecules but they are not compounds.

                      Petroleum is a crude mixture of variety of hydrocarbons containing carbon and hydrogen as a primary elements along with other hetero elements like nitrogen, oxygen and sulfur etc. Therefore, these hydrocarbons can be termed as compounds because they are made up of atleast two essential elements like hydrogen and carbon.

                       Secondly, the process of distillation works on the basis of difference in boiling points of the compounds present in Petroleum. Therefore, compounds with lower boiling point will evaporate first and will separate first from the mixture and vice versa.