Fill the blanks by choosing the correct word of the following: 1- Natural gas is called when it is almost pure methane , when other hydrocarbons are present, the natural gas is ..... 2- ............. this compound is the cause of soumness in natural gas. 3- The grain per cubic feet density measurement unit is used to 4- Heating value is necessary so that the consumer can properly set his 5- An ideal gas cannot be liquefied by the pressure and the temperature