Drugs will only increase your stress, unless a. you smoke marijuana b. you smoke tobacco c. prescribed to you by a doctor for treating stress d. you take a friend's anti-stress medication

Which statement describes covalent bases? they have hydroxide ions. they produce hydrogen ions. they are often amines. they are named the same as ionic compounds.

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

The zinc within a copper-plated penny dissolves in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can reach the zinc). the reaction between the acid and the zinc 2h+(aq)+zn(s)→h2(g)+zn2+(aq) . when the zinc in a certain penny dissolves, the total volume of gas collected over water at 25 °c is 0.947 l at a total pressure of 743 mmhg . (vapor pressure of water is 23.78 mmhg at 25 °c .) what mass of hydrogen gas is collected? answer in appropriate significant figures