In the case of STIs, the answer is a resounding NO! Pulling out, or withdrawal, isnât an effective method of STI prevention because most disease-causing microorganisms donât depend on ejaculation for transmission. A condom will only help prevent the spread of STIs if you put it on before sex and leave it on the entire time you are having sex.
All chemical substances are either solid, liquid or gas. The standard state of a chemical substance is its phase (solid, liquid, gas) at 25.0 Â°C and one atmosphere pressure. Two elements are liquid in their standard state: mercury and bromine. Eleven elements are gas in their standard state. All of the noble gases (He, Ne, Ar, Kr, Xe, Rn) as well the halogens flourine and chlorine. Hydrogen, oxygen and nitrogen are the others. All other elements are solid in their standard state.
Standard solution. In analytical chemistry, a standard solution is a solution containing a precisely known concentration of an element or a substance. A known weight of solute is dissolved to make a specific volume. It is prepared using a standard substance, such as a primary standard. Standard solutions are used to determine the concentrations of other substances, such as solutions in titration.