List of top Geology Questions on Geochronology asked in GATE GG

If the Rb-Sr isochron formed by a suite of gabbro samples has a slope of 0.0265, then the calculated age of the gabbro in million years is_____. (in integer).
[Use λ(87Rb) = 1.42 x 10-11 year-1]
The rate of spreading about a symmetric spreading center at the middle of a 4000 km wide sea is 40 mm/year. The spreading began $\underline{\hspace{1cm}}$ million years before present. [in integer]