What percentage of an iodine-131 sample remains after 22 days?

Why do sodium and neon have vastly different chemical and physical properties despite having similar atomic masses?

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

Convert the temperature of dry ice, –77 ∞c, into degrees fahrenheit and kelvin.