Why is hydrogen unique among the elements

What is the compound name for the formula [ru(en)2cl2]2+ and [co(en)cl2br]-

If there are 3.5 moles of koh, how many moles of naoh can be produced? question 1 options: a)3.0 moles naoh b)3.5 moles naoh c)1 moles naoh d)9 moles naoh

When did stem cell research become known ? who discovered stem cell? what experiments or studies have been conducted so far?