What are some natural resources that are limited on earth

Concentrations expressed as a percent by mass are useful when the solute is a a. liquid b. gas c. solid

Which of these describes how heat is transferred by convection* a. sunlight travels through space without the aid of fluids or solids. b. warm air rises and takes the heat with it, eventually, it cools and sinks c. air at the equator rises and sinks at the poles. d. air molecules touch the warm ground, heating them up *not conduction

How to draw a diagram to represent a calcium metal lattice?