NaK is an alloy of sodium and potassium that is very useful because it is liquid at room temperature, although precautions must be taken due to its extreme reactivity towards water and air.
nˈɑː kˈeɪ ɪz ɐn ˈælɔɪ ʌv sˈoʊdiəm ænd pətˈæsiəm ðæt ɪz vˈɛɹi jˈuːsfəl bɪkˈʌz ɪɾ ɪz lˈɪkwɪd æt ɹˈuːm tˈɛmpɹɪtʃɚ, ɔːlðˈoʊ pɹɪkˈɔːʃənz mˈʌst biː tˈeɪkən dˈuː tʊ ɪts ɛkstɹˈiːm ɹɪɐktˈɪvᵻɾi təwˈɔːɹdz wˈɔːɾɚ ænd ˈɛɹ.