What is the mass of an atom with 15 neutrons and 13 electrons ?

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

Alarge marble is dropped in a graduated cylinder with 35ml of water in it.the water level increases to 49ml.what is the volume of the marble

1) this is the structure in the cell nucleus that houses a cell's genetic information