When two substances with the same mass are heated by the same amount, which pair would heat up at about the same rate? Use the table to identify the substances. Substance C(J/g-°C) Water (ice) 2.05 Iron 0.46 Aluminium 0.90 Gold 0.13 Copper 0.39 Ammonia (liquid) 4.70 Ethanol 2.44 Gasoline 2.22 Water (liquid) 4.18 Water (vapor) 2.08 Air (25°C) 1.01 Oxygen 0.92 Hydrogen 14.30

iron and aluminum
gold and copper
copper and iron
aluminum and gold

the answer is d.) potassium

it is the minimum amount of material needed to sustain a fission reaction.

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.