How many valence electrons does selenium have?

A student dissolved 11 g of a solid solute, Q, into 67 g of a liquid solvent, R, at 50oC to form a clear solution. After 10 minutes, white crystals began to form in the solution.

1) How many grams of CO are needed to react with an excess of Fe2O3 to produce 225.5 gFe? Numbers after symbols are subscripts unless there is a ^ to show it is an exponent ... Fe2O3 (s) + 3CO (g) - - > 3 CO2 (g) + 2 Fe (s) ...

a solution is made by adding 27.5 g of calcium fluoride to enough water to make 1.00L. what is the concentration (molarity) ?

Can a hypothesis be accurately tested by performing one experiment?

Which of the following examples does NOT describe nuclear fission? Bombarding uranium nuclei with beta particles to produce two lighter atomic nuclei. Colliding hydrogen atoms to produce heavier helium atoms.

Convert 1.67 x10^24 atoms of carbon to moles of carbon

The knowledge of chemistry not important in one of the following? A, in agriculture B, in Geology C, in medicine D, none

Which is the balanced equation for: Al2O3 + Fe - Fe3O4 + AL

Why are lab apparatus made of ceramics

The volume of oxygen required for complete combustionof a mixture of 5 cm3 of ch4 and5 cm3 c2h4