Can someone help me with this

Light waves can move through , but they travel fastest when they move through a(n) .

Covalent bonds generally form when the bonded elements have a difference in electronegativity less than 1.5. subtract the electronegativities for the following pairs of elements and predict whether they form a covalent bond. electronegativity difference of c and c: ionic covalent electronegativity difference of mg and cl: ionic covalent

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1