Density gives mass of object per volume...... Here, density is given 8.90 g/cm3 therefore, per cubic centimeter contains 8.90 g Ni. mole of Ni = mass / atomic mass = 8.90 / 58.6934 = 0.1516 mole number of atoms: mole * 6.022 * 10^23 = 0.1516 * 6.022 * 10^23 = 0.9129 * 10^23 = 0.9 * 10^23 (approx.)
Answer:
B. an air-conditioning system.
Explanation:
Refrigeration is defined as a process of cooling a system to lower temperature below the surrounding temperature while the removed heat is rejected at higher temperatures.
Heat pumps use the heat output of the refrigeration process, which may also be designed to be reversible, but are otherwise similar to air conditioning units.
We want to solve Q = mcΔT for the liquid water; its change in temperature will tell us the amount of thermal energy that flowed out of the reaction. The specific heat, c, of water is 4.184 J/g °C.
Q = (72.0 g)(4.184 J/g °C)(100 °C - 25 °C) = 22593.6 J
Q ≈ 2.26 × 10⁴ J or 22.6 kJ (three significant figures).
