Answer:- Mass of the titanium alloy is 7.01 g, choice C is correct.
Solution:- The heat of fusion is given as 422.5 joules per gram and it also says that 2960 joules of heat is required to melt the metal completely.
The suggested equation is, 
where Q is the heat energy, m is the mass and Hf is the heat of fusion.
Since, we are asked to calculate the mass, the equation could be written as:

Let's plug in the values in it:

m = 7.01 g
So, the mass of the titanium alloy is 7.01 g, choice C is correct.
The balanced equation for the above reaction is as follows;
C + H₂O ---> H₂ + CO
stoichiometry of C to H₂O is 1:1
1 mol of C reacts with 1 mol of H₂O
we need to find which is the limiting reactant
2 mol of C and 3.1 mol of H₂O
therefore C is the limiting reactant and H₂O is in excess.
stoichiometry of C to H₂ is 1:1
then number of H₂ moles formed are equal to C moles reacted
number of H₂ moles formed = 2 mol
Answer:
second law of thermodynamics.
Explanation:
The second law of thermodynamics deals with interconversion of energy from one form to another. Although energy can be converted from one form to another, this conversion is never 100% efficient because energy is lost in certain ways such as through heat. In a combustion engine, it is not possible to recover the energy from the gasoline 100% since energy must be lost along the way via such means as heat losses. Hence I will be skeptical about such an advert.