Answer: Option (b) is the correct answer.
Explanation:
A change that does not lead to any difference in chemical composition of a substance is known as a physical change.
For example, shape, size, mass, volume, density, boiling point, etc of a substance are all physical properties.
Boiling of water is a physical change as it leads to conversion of liquid state of water into vapor state.
On the other hand, changes that lead to bring change in chemical composition of a substance is known as a chemical change.
For example, exploding dynamite, rotting cheese etc are all chemical changes.
Thus, we can conclude that the statement no, boiling water is a physical change is true when water is heated, bubbles form in the water. This evidence is not of a chemical reaction.
Answer: Iridium
Explanation:
The atomic number of Iridium is 77.
Answer:
Option C. 251 kJ
Explanation:
The activation energy (Ea) of a given reaction is the minimum energy that must be overcomed for reactant to proceed to product.
The activation energy (Ea) can be obtained from an energy profile diagram by simply calculating the difference between the energy of the activation complex (i.e the peak) and the energy of the reactant.
Thus, we can obtain the activation energy for the reaction above as follow:
Activation complex = 332.6 kJ
Energy of reactant = 81.6 kJ
Activation energy =?
Activation energy = Activation complex – Energy of reactant
Activation energy = 332.6 – 81.6
Activation energy = 251 kJ
Therefore, the activation energy of the reaction is 251 kJ
Answer:
26.74g
Explanation:
The equation of the reaction is;
SIO₂ + 3C --> SiC +2CO
From the balanced equation, the relationship between SiC and C is;
3 mol of C produces 1 mol of SiC
Converting mol to mass using; Mass = moles * Molar mass
Mass of SiC = 1 mol * 40.11 g/mol = 40.11g
This means;
3 mol of C produces 40.11g of SiC
2 mol of C produces xg of SiC
3 = 40.11
2 = x
x = 2 * 40.11 / 3 = 26.74g
Answer : The equilibrium concentration of 
is, 0.50 M
Explanation : Given,
Initial moles of = 0.65 mole
Volume of solution = 1.0 L
Moles of 
at equilibrium = 0.15 mole
The balanced equilibrium reaction will be,
Initial moles 0.65 0 0
At eqm. (0.65-x) x x
Moles of at equilibrium = x = 0.15 mole
Moles of 
at equilibrium = x = 0.15 mole
Moles of at equilibrium = (0.65-x) = (0.65-0.15) = 0.50 mole
Now we have to calculate the concentration of 
at equilibrium.
Formula used : 
Therefore, the equilibrium concentration of is, 0.50 M
