What element is used as a shield to protect people from radioactive substances?

Which ion has the smallest radius? (1) O2- (2) S2- (3) Se2- (4) Te2-

The width of a football field is 160 ft. How many meters is this?

Solar homes often use water to collect heat from the sun. If the same amount of heat was used on 2500 kg of water in one house and 1500 kg of water in a second house, what will happen? The 2500 kg of water will reach a higher temperature.

What is the maximum number of moles of Al2O3 that can be produced by the reaction of. 4 mol of Al with. 4 mol of O2

Heat can be transferred through conduction, convection, and radiation. What is necessary in order for heat to be transferred by conduction?

Four moles of hydrogen chloride (HCl) gas react with one mole of oxygen (O2) gas to produce two moles of chlorine gas (Cl2) and two moles of water gas (H2O).

The density of rubbing alcohol is 0.785g/mL at 25 Celsius. Calculate the mass of 15.0 mL of the rubbing alcohol.

Is the universe an isolated system?

1000ml of a gas is cooled from 500 K to 250 K, what is it's final volume? A. 250 ml B. 1000 ml C. 500 ml D. 750 ml E. 2000 ml

A reacton has a theoretical yield of 22.8g. When the reaction was carried out, 15.1g of the product was obtained. What is the percent yield?