Why do acid-catalyzed and base-catalyzed sol-gel processes result in linear and branched metal oxides, respectively

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

What is the molar mass of a gas that has density of 2.054 g/l

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?