Direct system
Indirect system
Cross system
Isolated system
Soap and water
Burning candle
Sulphur sticks
Halide torch
Freon-12
Carbon-dioxide
Ammonia
Sulphur dioxide
It does not contain impurities
It is solidified form of Carbon dioxide
It is free from water
None of the above
0 degree celsius
4 degree Celsius
100 degree celsius
0 degree kelvin