What is the mass of 6.02x10^23 potassium atoms?

Acalorimeter is to be calibrated: 51.203 g of water at 55.2 degree c is added to a calorimeter containing 49.783 g of water at 23.5c. after stirring and waiting for the system to equilibrate, the final temperature reached is 37.6 degree c. specific heat capacity of water (s = 4.18 j/g∙degree c). calculate the calorimeter constant. (smδt)warm water = -[(smδt)cold water + (calorimeterδtcold water)]

0.070g of hydride of carbon occupies 56cm^3 at s.t.p when vaporized and contained 14.29% by mass of hydrogen.what is the formula for the hydrocarbon

When utilizing a transmission electron microscope, why is it necessary to stain the specimen with heavy metal salts?