Answer:
The gravitational potential energy it had from being above the ground is converted to kinetic energy as the rock falls. As kinetic energy increases, the velocity of the rock will also increase. However, if one considers the air, the rock will lose energy as it falls due to air resistance. If the cliff is high enough, the acceleration due to gravity and the air resistance due to the velocity will be exactly equal and there will be no change in kinetic energy.
Explanation:
hope this helps
Answer : The value of
for the reaction is, -135.2 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation of
will be,

The intermediate balanced chemical reaction will be,
(1)

(2)

(3)

We are dividing the reaction 1, 2 and 3 and reversing reaction 3 and then adding all the equations, we get :
(1)

(2)

(3)

The expression for enthalpy of formation of
will be,



Therefore, the value of
for the reaction is, -135.2 kJ
The molar mass of Naphthalene is 128g/mol
Therefore; a mass of 1.64 g of Naphthalene contains'
= 1.64g/128 g
= 0.0128 moles
But, from the Avogadro's law 1 mole of a substance contains 6.022 × 10^23 particles
Therefore 1 mole of Naphthalene contains 6.022×10^23 molecules
Hence; 0.0128 moles × 6.022 ×10^23 molecules
= 7.716 × 10^21 molecules