The mass of iron block is 500 g. The amount of energy required to melt the iron block needs to be calculated. Melting means conversion of solid to liquid thus, heat of fusion is used which is 247 J/g.
From heat of fusion, 247 J of energy is released by melting 1 g of iron block. Thus, the amount of heat released by melting 500 g of iron rod will be:
H= 247 J/g× 500 g=1.23×10^{5}
Hence, option B is correct.
Answer : The mole fraction of nitrogen will be 0.4615.
Explanation : When nitrogen (
)and hydrogen (
)are mixed, the mole ratio becomes 1 : 1.5,
Now we know that () is acting as a limiting agent.
So at the time of when 0.4 moles of (
) is been formed it requires 0.4 moles of () and 3.4 moles of ()
So, we find the the remaining () will be 0.6 and
() will be 0.3 mole present in mixture.
So, the mole fraction of () becomes = 0.6 / (0.6 + 0.4 + 0.3) Which becomes = 0.4615
Answer = c
Conservation of mass (mass is never lost or gained in chemical reactions), during chemical reaction no particles are created or destroyed, the atoms are rearranged from the reactants to the products.
Answer:
Both reaction A and reaction B are non spontaneous.
Explanation:
For a spontaneous reaction, change in gibbs free energy (
) should be negative.
We know, 
, where T is temperature in Kelvin scale.
Reaction A: 
As is positive therefore the reaction is non-spontaneous.
If at a temperature T K , the reaction is spontaneous then-
or, 
or, 
or, 
So at a temperature greater than 350 K, the reaction is spontaneous.
Reaction B: 
As is positive therefore the reaction is non-spontaneous.
If at a temperature T K , the reaction is spontaneous then-
or,
or, 
or, 
So at a temperature greater than -16 K, the reaction is spontaneous.
