( ( ( ( That ( 's ( because ( ice ( ( ( takes up ) ( more room ) ) ( than ( ( the water ) ( ( from which ) ( it ( 's formed ) ) ) ) ) ) ) ) ) ) -- ) ( ice ( is ( less ( dense ( than water ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT That)) (VP (VBZ 's) (SBAR (IN because) (S (NP (NN ice)) (VP (VBZ takes) (PRT (RP up)) (NP (JJR more) (NN room)) (PP (IN than) (NP (NP (DT the) (NN water)) (SBAR (WHPP (IN from) (WHNP (WDT which))) (S (NP (PRP it)) (VP (VBZ 's) (VP (VBN formed)))))))))))) (: --) (S (NP (NN ice)) (VP (VBZ is) (ADJP (RBR less) (JJ dense) (PP (IN than) (NP (NN water)))))) (. .)))
That's because ice takes up more room than the water from which it's formed--ice is less dense than water.
(ROOT (S (NP (NNP Water)) (VP (VBZ takes) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NN ice)))) (PP (IN on) (NP (NN planet) (NNS mars)))) (. .)))