__ 5. Which of the following would require the least amount of heat to raise its temperature by 20^circ C A. 400gof motor oil B. 400gof sand C. 400gof water D. 400gof iron

The amount of heat required to raise the temperature of a substance is given by the equation:<br /><br />Q = mcΔT<br /><br />where:<br />* Q is the heat energy<br />* m is the mass of the substance<br />* c is the specific heat capacity of the substance<br />* ΔT is the change in temperature<br /><br />We are given that the mass (m) and the change in temperature (ΔT) are the same for all substances. Therefore, the substance that requires the least amount of heat will be the one with the lowest specific heat capacity (c).<br /><br />Here are some typical specific heat capacities:<br /><br />* Water: 4.18 J/g°C<br />* Iron: 0.45 J/g°C<br />* Sand: 0.83 J/g°C (approximately, varies depending on composition)<br />* Motor Oil: ~1.7 J/g°C (approximately, varies depending on type)<br /><br />Comparing these values, iron has the lowest specific heat capacity.<br /><br />Therefore, the answer is **D. 400g of iron**.<br />