Aradioactive nuclide that is used for geological dating has an atomic number of 19 and mass number 40. which is the symbol of this nuclide?

Asample of radium-226 will decay 1/4 of its original amount after 3200years. what is the half-life of radium-226?

Sarah wants to know where in her garden chamomile would grow the best. she thinks chamomile will grow best in the corner of the garden that gets the most sunlight. to test her hypothesis, she decides to plant several groups of chamomile in her garden as an experiment. which of the following variables will sarah need to measure to know which group of plants grew best? a. the location of the plants b. the type of plants c. the height of the plants d. the amount of water she gives the plants

What is the temperature of one mole of helium gas at stp?