Answer:
43.89 min
Explanation:
Given that:-
The speed of light = 
The distance = 
The conversion of distance in km to distance into m is shown below as:-
1 km = 1000 m
So,
Distance = 
The relation between speed distance and time is shown below as:-

Thus,


Time = 2633.33 seconds
Also, 1 s = 1/60 min
So,
Time=
Answer: 250 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 Hess’s law, the chemical equation can be treated as algebraic expressions 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.
(1)
(2)
Net chemical equation:
(3)
Adding 1 and 2 we get,
(4)
Now dividing equation (4) by 4, we get
(4)
A mole contains Avogadro’s number of particles of a substance.
Answer : The balanced equation for the complete combustion of cyclopentane will be :

Explanation :
As we know that the hydrocarbons can undergo complete or incomplete combustion that depends on the amount of oxygen available.
Complete combustion : It takes place when there is a good supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon dioxide and water as a product.
The general reaction will be :

Incomplete combustion : It takes place when there is a poor supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon monoxide, carbon dioxide and water as a product.
The general reaction will be :

As per question, the complete combustion of cyclopentane react with oxygen to gives carbon dioxide and water as a product.
Therefore, the balanced chemical reaction will be :
