Metal Malleability: Shaping by Finger Pressure

The question asks to identify a metal soft enough to be shaped into leaves using only finger pressure. This property is known as malleability, which is the ability of a metal to deform under compressive stress without fracturing.

Evaluating Metal Properties

• Iron: Iron is a relatively strong and hard metal. It requires significant force and tools, like hammers or rolling mills, to be shaped. It cannot be shaped by finger pressure.
• Silver: Silver is a highly malleable and ductile metal, second only to gold in malleability among common metals. However, shaping it into thin leaves typically requires specialized techniques like hammering or rolling, not just finger pressure.
• Sodium: Sodium is an alkali metal. Alkali metals are known for being extremely soft and reactive. Sodium is soft enough to be easily cut with a knife at room temperature and can indeed be deformed or pressed into thin sheets (akin to leaves) with relatively low force, such as finger pressure.
• Gold: Gold is the most malleable of all metals. It can be beaten into extremely thin gold leaf. However, this process requires meticulous hammering and specialized tools, not simple finger pressure. While it achieves 'leaf' form, the method specified in the question points towards a softer metal.

Conclusion on Metal Softness

Comparing the options, sodium stands out due to its exceptional softness. While gold is the most malleable overall, the specific condition "pressure of the fingers" strongly suggests a metal with very low resistance to deformation, which is characteristic of sodium among the choices provided.

Therefore, sodium is the metal that can be shaped into leaves by the pressure of the fingers.