What is an object that stops electrons from completing the circuit

Your 249 ml cup of coffee is too hot to drink when served at 82 degree celsius. what is the mass of an ice cube taken from a -21 degree celsius freezer, that will cool your coffee to a pleasant 54 degree celsius. specific heat of the water is 4190 j/kg c, specific heat of ice is 2090 j/kg c, heat of fusion of ice is 3.33 x 10^5 j/kg

The air that we breath is made mostly of which gaseous molecule

Your town is considering building a biodiesel power plant describe at least two advantages and two disadvantages