If A is a radioactive element which emits an α -particle and produces Rf 104 259 . Write the atomic number and mass number of the element A .

α -particle is equivalent to Helium nucleus consisting of two protons and two neutrons. If A is a radioactive element which emits an α -particle and produces Rf 104 259 . We can write the equation of this reaction as: A Z A → α - decay Y Z - 2 A - 4 + He 2 4 . A Z A → α - decay Rf 104 259 + He 2 4 . A - 4 = 259 , Z - 2 = 104 . ∴ A = 263 , Z = 106 . The atomic number is 106 and mass number is 263 .

If A is a radioactive element which emits an α -particle and produces Rf 104 259 . Write the atomic number and mass number of the element A .

α -particle is equivalent to Helium nucleus consisting of two protons and two neutrons. If A is a radioactive element which emits an α -particle and produces Rf 104 259 . We can write the equation of this reaction as: A Z A → α - decay Y Z - 2 A - 4 + He 2 4 . A Z A → α - decay Rf 104 259 + He 2 4 . A - 4 = 259 , Z - 2 = 104 . ∴ A = 263 , Z = 106 . The atomic number is 106 and mass number is 263 .

Roentgen is a unit of radiation exposure. One roentgen is defined as the quantity of radioactive substance which produces a charge of 2 . 58 × 10 - 4 C in 1 kg of air under standard conditions of temperature, pressure and humidity.