Radioactive iodine isotope of half-life 8.0 days is used for the treatment of thyroid gland cancer. A certain sample is required to have an activity of 80 x 10^5 Bq at the time it is
given to the patient. Calculate the mass of the iodine-131 present in the sample to produce the required activity. Given the mass of iodine is 131g.​

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)

An atom that has gained or lost electrons is called an _

Which of the the following are examples of projectile motion of both projectile motion and two dimensional motion