If element x bonds covalently with element y, then what must the electronegativity difference between x and y be for this bond to be nonpolar?

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

Which description best characterizes the motion of particles in a solid?

How can a give a full method for the experiment of separating sand from water by filtration? 1-materials 2-steps 3-conclusion also for water and salt separated by the evaporation or distillation process