Limiting reactants would appreciate if somebody could help me don’t understand

Which of the following pressures is equal to 760 mm hg? 2.0 atm 101.3 pa 101,300 kpa 101,300 pa

Determine the percent sulfuric acid by mass of a 1.61 m aqueous solution of h2so4. %

Explain why pure hydrogen cyanide does not conduct electricity, but become a conductor when it is dissolved in water? (at room temp, pure hcn exists as a volatile liquid)