What mass of helium is in a 2.00L ballon at STP

When working with food, personal items such as a cell phone should be

The US. quarter has a mass of 5.67 g and is approximately 1.55 mm thick (a) How many quarters would have to bestacked to reach 575 ft, the height of the Washington Monument? (b) How much would this stack weigh?

Is a compound a mixture

What derived unit is usually used to express the density of liquids?

A 25.00 g solid sample of Ca (OH) 2 was added into 1250 mL of 0.400 M HCl aqueous solution. The temperature of the solution was decreased from 36.6oC to 20.0oC. Assuming Ccal of the reaction is 5.225 kJ/oC, how much heat is involved in the reaction?

Carbonic acid (H2CO3) does not dissortate 100 percent in water. What type of substance is it? weak acid Strong base strong acid weak base

The standard enthapy of combustion of solid urea co (nh2) 2 is - 632kjmol-1 at 298k

What happens to an isotopes during radioactive

Why does the effective nuclear charge increase across a row of the periodic table?

Iodine-131 decays to form xenon-131. the half-life of this reaction is 8.07 days. from a 200-g sample of iodine-131, how much of the sample is xenon-131 after 16.14 days?