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NEET Questions / Chemistry / General Principles And Processes Of Isolation Of Elements
In an Ellingham diagram, the slope of the line for the formation of a metal oxide is positive. This indicates that:
The entropy change for the reaction is negative.
The reaction becomes less spontaneous at higher temperatures.
The free energy change becomes more negative at higher temperatures.
The enthalpy change for the reaction is positive.
Which of the following is NOT a limitation of the Ellingham diagram?
It doesn't show the effect of pressure on the reaction.
It assumes that the reactants and products are in their standard states.
It doesn't provide information about the kinetics of the reaction.
It doesn't account for the formation of solutions between metals and oxides.
The Ellingham diagram for the formation of metal oxides shows a sudden change in slope for some metals. This is due to:
Phase transition of the metal.
Change in the oxidation state of the metal.
Formation of a non-stoichiometric oxide.
Change in the partial pressure of oxygen.
In an Ellingham diagram, a line with a more negative slope than another indicates:
A larger increase in entropy during the reaction.
A smaller increase in entropy during the reaction.
A more negative enthalpy change for the reaction.
A less negative enthalpy change for the reaction.
The Ellingham diagram predicts the feasibility of reduction of metal oxides by:
Comparing the relative positions of the lines for the metal oxide and the reducing agent.
Calculating the exact value of the equilibrium constant for the reaction.
Determining the activation energy for the reduction reaction.
Measuring the enthalpy change of the reaction.
For the reaction , the Ellingham diagram shows a negative slope. This is primarily because:
The number of gaseous molecules increases during the reaction.
The reaction is exothermic.
Carbon is a good reducing agent.
Carbon monoxide is a stable gas.
Which of these processes is NOT commonly used for the extraction of metals from their ores?
Roasting
Calcination
Smelting
Fractional distillation
Calcination is the process of heating ore in the absence of air. What is its primary purpose?
To oxidize the ore.
To decompose carbonates and hydrates in ores.
To reduce the ore.
To purify the ore by removing volatile impurities.
Which of the following is an example of an ore that is commonly roasted?
Calcium carbonate (CaCO3)
Iron oxide (Fe2O3)
Zinc sulfide (ZnS)
Aluminum oxide (Al2O3)
Smelting involves heating the ore with a reducing agent. Which of the following is commonly used as a reducing agent in smelting?
Oxygen
Water
Coke
Sodium chloride