The half-life of a sample of a radioactive substance is 1 hour. If \[8\times {{10}^{10}}\] atoms are present at \[t=0\], then the number of atoms decayed in the duration \[t=2\] hour to \[t=4\] hour will be

• A. \[2\times {{10}^{10}}\]
• B. \[1.5\times {{10}^{10}}\]
• C. Zero
• D. Infinity