Is quartz (SiO2) a substance or mixture?

The sun and stars give off radiant energy. Observation of a star's radiant energy enables us to study the star's composition and which factor? A. the number of stars in its galaxy B. the distance to the center of its galaxy C.

What what is any harm to the physical chemical or biological health of the ocean ecosystem

In chemical reactions, there is a conservation of what?

A 12.39 g sample of phosphorus reacts with 42.54 g of chlorine to form only phosphorus trichloride (pcl3). if it is the only product, what mass of pcl3 is formed?

How does a change in frequency or amplitude change the sound we hear

A certain first-order reaction (A→productsA→products) has a rate constant of 9.90*10-3 s-1s-1 at 45 ∘C∘C. How many minutes does it take for the concentration of the reactant, [A][A], to drop to 6.

Assign the oxidation number for (NH4) 3PO4

When gold is melted and formed in a mold to make a piece of jewelry, what type of change is taking place?

Do pure substances have the same chemical and physical properties

How is matter conserved in a chemical reaction