Asmall pebble is heated and placed in a foam cup calorimeter containing 25.0 ml of water at 23.0°c. the water reaches a maximum temperature of 24.2°c. how many joules of heat were released by the pebble? (the specific heat capacity of water is 4.18 j/g•°c and the density of water is 1.00 g/ml)

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.