181) The absolute zero pressure can be attained at a temperature of

182) One kg of ethylene (C₂H₄) requires 2 kg of oxygen and produces 22/7 kg of carbon dioxide and __________ kg of water or steam.

183) One m³ of methane (CH₄) requires 2m³ of oxygen and produces 1m³ of carbon dioxide and 2m³ of water or steam.

184) Coke oven gas is obtained by burning coke in an oven.

185) A perpetual motion machine of the first kind is __________ according to first law of thermodynamics.