What is the formula for calculating pH?

Which type of reaction always has an element and a compound as reactants

Drag each number to the correct location on the equation. each number can be used more than once, but not all numbers will be used. balance the equation with the coefficients. 2 3 4 5 kclo3 -> kcl + o2

This element exists in adundance in the sun.explain how you would go about capturing sunlight.would this captured sunlight contain any of the element?