Bubbles of ${\text{H}}_{\text{2}}$ form when metal D is placed in hot . No reaction occurs when D is placed in a solution of a salt of metal E, but D is discoloured and coated immediately when placed in a solution of a salt of metal F. What happens if E is placed in a solution of a salt of metal ? Rank metals, E, and F in order of increasing reducing strength.

The ability of a material to bear an applied load without failure or plastic deformation is known as its strength in material mechanics. The field of material strength is concerned with the forces and deformations that occur when they act on a material.

When reacted with ${\text{H}}_{\text{2}}\text{O}$, metal D is a better reducing reagent since hydrogen bubbles form. When D and E react, no reaction occurs, therefore a better reducing agent because D is not oxidized. When D and F are reacted, D is discoloured, therefore it has a stronger reducing power than F because F was reduced in its reaction.

If metal E and salt of F are mixed together, it is expected that F metal will be produced because E has a stronger reducing power than D metal, which means it will also be more powerful than the F metal. In order of increasing strength, F is the least powerful reducing agent among the three, followed by D, and E is the strongest among the three.

Therefore, the order of increasing strength is$F<D<E$ .