Answer:
d). A catalyst lowers the activation energy for a chemical reaction.
Explanation:
From the given choices, it is true that a catalyst lowers the activation energy for a chemical reaction.
The activation energy is the energy barrier that must be overcome before a chemical reaction can occur.
Some reactions have very high activation energy and would not occur without the introduction of a catalyst.
The catalyst brings the reactants into contact by removing the energy deficiency in the system.
Answer:
1 g of Carbon
Explanation:
This is because because carbon has lower molar mass than thorium or copper so a 1-g sample of carbon contains more atoms than 1 g of cobalt or lead.
Explanation :
As we know that the Gibbs free energy is not only function of temperature and pressure but also amount of each substance in the system.
where,
is the amount of component 1 and 2 in the system.
Partial molar Gibbs free energy : The partial derivative of Gibbs free energy with respect to amount of component (i) of a mixture when other variable 
are kept constant are known as partial molar Gibbs free energy of 
component.
For a substance in a mixture, the chemical potential 
is defined as the partial molar Gibbs free energy.
The expression will be:
where,
T = temperature
P = pressure
is the amount of component 'i' and 'j' in the system.
