Answer : The fuel value and the fuel density of pentane is, 49.09 kJ/g and
respectively.
Explanation :
Fuel value : It is defined as the amount of energy released from the combustion of hydrocarbon fuels. The fuel value always in positive and in kilojoule per gram (kJ/g).
As we are given that:

Fuel value = 
Molar mass of pentane = 72 g/mol
Fuel value = 
Fuel value = 49.09 kJ/g
Now we have to calculate the fuel density of pentane.
Fuel density = Fuel value × Density
Fuel density = (49.09 kJ/g) × (0.626g/mL)
Fuel density = 30.73 kJ/mL = 
Thus, the fuel density of pentane is 
The atoms undergo chemical changes.
New substances may be a product of the reaction.
<span>The characteristics of a wave are given certain names to describe them, and this helps scientists to accurately describe any given wave. The characteristic known as frequency describes the number of waves that pass a point, and it is measured in waves per second, or Hertz, which is given the symbol Hz, but can also be described using the inverse of the SI unit for second, s^-1.</span>
Physical......................................................
Answer: 1
1.Cl K Ar is in order
2.Fe Co Ni isn't in order
3.Te I Xe isn't in order
4.Ne F Na isn't in order