Rubidium , beta decay

All naturally occurring rubidium cores contain 87Sr, resulting from the beta decay of 87Rb. In naturally occurring rubidium, 278 of every 1000 rubidium atoms are 87 Rb. A mineral containing 0.85% rubidium was analyzed and found... 

The beta decay scheme of rhenium-187 to osmium-187 maybe applied to the study of sulfide minerals of molybdenum and osmium-rich minerals such as iridosmine. Together with rubidium/strontium, samarium/neodymium, lutetium/hafnium, and uranium/lead methods, it has been used to examine mantle differentiation and the accretion of continental crust. In molybdenites, rhenium concentrations vary from a few ppm to as much as 1.88%. The element has two naturally occurring isotopes, and these are the stable rhenium-185 with a relative abundance of 37.398% and the radioactive rhenium-187 with a relative abundance of62.602%. This decays as follows ... 

The naturally occurring isotope rubidium-87 decays by beta emission to strontium-87. This decay is the basis of a method for determining the ages of rocks. A sample of rock contains 102.1 /rg Rb and 5.3 /xg Sr. What is the age of the rock The half-life of mbidium-87 is 4.8 X 10 y. 

Rubidium-87, which forms about 28% of natural rubidium, is radioactive, decaying by the emission of a single beta particle to strontium-87. Write the nuclear equation for this decay of rubidium-87. 

---