Hi guys please help me what is the chemical formula of potassium react with oxygen

Niobium forms a substitutional solid solution with vanadium. compute the number of niobium atoms per cubic centimeter for a niobium-vanadium alloy that contains 24 wt% nb and 76 wt% v. the densities of pure niobium and vanadium are 8.57 and 6.10 g/cm3, respectively

The place you get your hair cut has two nearly parallel mirrors 6.00 m apart. as you sit in the chair, your head is 2.00 m from the nearer mirror. looking toward this mirror, you first see your face and then, farther away, the back of your head. (the mirrors need to be slightly nonparallel for you to be able to see the back of your head, but you can treat them as parallel in this problem.) how far away does the back of your head appear to be?

All the simple machines make work easier to do by changing the or of a force. a. size; type b. work; type c. size; direction d. type; direction