The rate constant for a particular second-order reaction is 0.47 M-1sec-1. If the initial concentration is 0.25 M, how much time is needed for a concentration to decrease to 0.13 M?

No. an alpha particle is a pair of protons and a pair of neutrons, i.e. a helium

Answer///precipitate;

English , i don't understand spanish.

3-isopentane; 3-methylbutane, and 1,2-methylpropane do not meet iupac rules, so they are wrong names.the only valid name onthe list is 2-methylbutane, which is the same isopentane.this is its formula:                   ch2                    |ch3 - ch - ch2 - ch3answer: 2-methylbutane