The table gives some properties of transition elements and explains why they have them. Which row shows a correct property and the reason transition elements display this property?
- Airon has two common oxidation states (I) and (II) / iron atoms can lose one or two electrons to form compounds
- Bnickel can be used as a catalyst / the use of nickel raises the activation energy of the reaction
- Cthe reaction of aqueous sodium hydroxide with the salt of a transition element can be used to identify the element / transition metal hydroxides are often coloured
- Dtransition elements have high melting points / the presence of varying numbers of electrons in the ‘sea’ of delocalised electrons weakens the metallic lattice