What is the function of the objective lens of are refracting telescope?

Ahypothrticalax type of ceramic material is known to have a density of 2.10 g/cm3 and a unit cell of cubic symmetry with a cell edge length of 0.57 nm. the atomic weights of the a and x elements are 28.5and 30.0 g/mol, respectively. on the basis of this information, which of the following crystal structures is (are) possible for this material: sodium chloride, cesium chloride, or zinc blende

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion