Chem 高手請答~~

1.At room temperature and pressure ,12 dm^3 of hydrogen and 6 dm^3 of oxygen combine to give 6dm^3 of water.

呢句 sentence is wrong y ge??
I know that water is liquid ,so it's vol 會比calculate 出少,
but solution 寫 少過6dm^3 ....
y not 小過12 dm^3?? 2mol H2 react with 1mol O2 to give 2mol water.
e+ 有12 dm^3 H2 ,y not give < 12dm^3 water??而係give < 6dm^3 water?

2. 可唔可以教我畫1,1,1- trichloroethane??
我唔明dH ge 數量點分布,同埋點解比計個個小左H.thz!!!!

plz!!!!!!!!!!