The radioactive isotope technetium-99 in an excited state ( 9943tcm or tc-99m) can be used in medicine to determine a patient's blood volume. tc-99m emits gamma-rays and has a half-life t1/2 = 6.0h. a sample of tc-99m of mass 7.7x10-14kg is injected into the patient's circulatory system. 1.0 h after the injection, 20 cm³ of blood is taken from the patient. the activity of this sample is measured to be 55 kbq. calculate the patient's blood volume. show with explanations.

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.