Name three devices or inventions which are designed to decrease friction

Which of the following statements is false regarding aromaticity? a. the compound must be cyclic b. the compound must be fully conjugated c. the compound must be planar d.the number of electrons in the pi system must satisfy the hückel 4n+2 rule e. the compound must have a neutral charge

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6

Select all the correct answers.which compounds have the empirical formula ch20? (multiple answers)a.c2h4o2b.c3h603c.ch2o2d.c5h1005e.c6h1206