12. a football match is being played at night in a stadium with flood lights on. you can see the shadow of a football kept at the ground but cannot see its shadow when it is kicked high in the air. explain.

Sylvanite is a mineral that contains 28.0% gold by mass. how much sylvanite would you need to dig up to obtain 77.0 g of gold? explain how you got your answer and the steps you took. you

The answer for #3 is c but i don't know why

Which formula can be used to calculate the molar mass of ammonia (nh3)? molar mass of n + molar mass of h 3 × molar mass of n + molar mass of h molar mass of n + 3 × molar mass of h 3 × molar mass of n + 3 × molar mass of h