What is the half-life of a radioisotope? a. the amount of time it takes for half of the material to decay b. the amount of time a radioisotope exists as the parent element c. the amount of time it takes for a radioisotope to get halfway to a stable form d. the amount of time it takes for half of the radioisotope to form

The diagram shows the positions of the sun, moon and earth during spring tides, when the high tides are at their highest and low tides at their lowest. what is it about these positions that causes these high and low tides?

What is the ph of a 0.0010 m hno3? 1.0 3.0 4.0 5.0

Cryolite, na3alf6(s), an ore used in the production of aluminum, can be synthesized using aluminum oxide. start this question by first balance the chemical equation.1.) balance the equation: - alo3(s)+naoh(l)+hf(> na3alf6+h2o(g). 2.) if 17.5 kilograms of al2o3(s), 51.4 kilograms of naoh(l), and 51.4 kilograms of hf(g) react completely, how many kilograms of cryolite will be produced? 3.)which reactants will be in excess, (al2o3, naoh, or hf) 4.)what is the total mass of the excess reactants left over after the reaction is complete in kg?