The number of semester credit hours required for an associate degree depends on the college and degree program. In general, an associate degree takes two years full time and represents half the work required for a bachelor's degree.
A dekatherm (dth) is a unit of energy used primarily to measure natural gas, developed in about 1972 by the Texas Eastern Transmission Corporation, a natural gas pipeline company. It is equal to 10 therms or 1,000,000 British thermal units (MMBtu).
natural gas is methane CH4, and what you call burning is a combustion, it means: a reaction with the dioxygen O2 in the air when the mixture of air and methane is heated (with an electrical spark typically or with the flame of a match). The equation of this reaction is the following :