Uranium disintegrates at a rate proportional to the amount present at any time instant. If a and b grams of uranium are present at times t & t respectively. What is the expression for the half life of uranium?

• A. ( frac{(t +t )log2}{log u2061( frac{b}{a})} )
• B. ( frac{(t -2t )log2}{2log( frac{a}{b})} )
• C. ( frac{(t +t )}{2log( frac{a}{b})} )
• D. ( frac{(t -t )log2}{log u2061( frac{b}{a})} )