For equal masses of substances, which of the following has the highest specific heat capacity?

Introduction / Context:
This question deals with the concept of specific heat capacity in physics. Specific heat capacity tells us how much heat a substance must absorb to raise the temperature of 1 kg of the substance by 1 degree Celsius. Water is famous for having a high specific heat compared to most metals and many common liquids. Questions like this connect basic thermodynamics to everyday phenomena, such as why coastal climates are milder or why water heats and cools slowly.

Given Data / Assumptions:

• We compare equal masses of four substances: iron, water, gold, and benzene.
• The question asks which has the highest heat capacity; in exam context this usually means highest specific heat capacity.
• We assume standard temperature ranges where tabulated specific heat values apply.

Concept / Approach:
Specific heat capacity (c) is defined by the relation Q = m * c * ΔT, where Q is heat absorbed, m is mass, and ΔT is temperature change. For equal masses and equal temperature rise, the substance with the largest c requires the most heat. Water has a specific heat capacity of about 4.18 J/g°C, which is much higher than that of metals like iron and gold and generally higher than many organic liquids. Therefore, among the listed substances, water has the greatest specific heat capacity.

Step-by-Step Solution:
Step 1: Recall approximate specific heat values: water ≈ 4.18 J/g°C; iron ≈ 0.45 J/g°C; gold ≈ 0.13 J/g°C. Step 2: Recognise that metals typically have relatively low specific heats compared to water. Step 3: Organic liquids like benzene have specific heats lower than water, typically around 1–2 J/g°C. Step 4: Compare all four: water's specific heat is clearly the highest among them. Step 5: Conclude that for equal masses and equal temperature changes, water will absorb the most heat, so it has the greatest heat capacity.

Verification / Alternative check:
We can cross check this with everyday observations. Metals such as iron and gold heat up quickly when exposed to a flame, indicating they need relatively little energy to change temperature. Water, by contrast, takes a long time to boil, showing that it requires a lot of energy to raise its temperature. Coastal areas, where large bodies of water moderate the climate, also illustrate water's high heat capacity. Benzene and similar liquids warm faster than water under the same heating, again suggesting lower specific heat. All this supports water as the correct answer.

Why Other Options Are Wrong:
An iron piece: Iron has a much lower specific heat capacity than water, so it heats and cools more quickly. A gold piece: Gold has an even lower specific heat capacity than iron, making this option clearly incorrect. Benzene: An organic liquid with lower specific heat than water; it does not store as much heat per unit mass per degree. None of the above: Incorrect because water is included and is known to have the highest specific heat among the given choices.

Common Pitfalls:
Some students may misinterpret heat capacity as simply relating to how hot something feels to the touch, without considering mass and specific heat. Others might be unsure about benzene's properties and overestimate its specific heat. To avoid such mistakes, remember the general rule: water has a very high specific heat compared to most substances, particularly metals, which is why it is often used as a coolant and temperature stabiliser in nature and technology.

Final Answer:
For equal masses, water has the highest specific heat capacity among the substances listed.