What is the mass of 4.1 x 10^25 atoms of iron

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

How does the principle of electromagnetism explain the interaction between earth’s magnetic field and the solar wind?

According to the valence shell electron pair repulsion (vsepr) theory, a molecule that has four electron groups around the central atom will exhibit what electron geometry? view available hint(s) according to the valence shell electron pair repulsion (vsepr) theory, a molecule that has four electron groups around the central atom will exhibit what electron geometry? trigonal bipyramidal tetrahedral square planar determination of electron geometry requires information on whether the electron groups are lone pairs or bonding groups.