The half-life of a specific element was calculated to be 5200 years. what percentage of a sample of the pure element will remain after two half-lives?

Which statement justifies that hydrogen peroxide (h2o2) is a polar molecule? the o – h bond is nonpolar and the molecule is asymmetric. the o – h bond is nonpolar and the molecule is symmetric. the o – h bond is polar and the molecule is asymmetric. the o – h bond is polar and the molecule is symmetric.