Making pencils or transferring electricity in factories.
They found it ery useful
As useful as a lead balloon
A pencil lead - it becomes sharper and more useful for precise writing when it is broken.
How is the more useful question. Why might be useful in some contexts (Why is my equipment not functioning? Answer: It is not plugged in.] The danger is that the question why can lead you down many dead ends. It is more likely that how will lead you to explore what is properly within the paradigm of science.
Variations in organisms can certainly be useful in plant and animal breeding. These variations lead to adaptions to the environment.
Lead is a metal element. Atomic mass of it is 207.
isotopes
Lead can be used as a pure metal, alloyed with other metals or as a chemical compound. Lead is a major component of the lead acid battery and is commonly used in a car battery. It is used in the battery of a phone, which is a very important material for a phone.
Yes, lead is radiopaque, which means it is visible on X-rays and other imaging techniques. This property makes lead useful in various medical applications, such as shielding in radiology and protection from ionizing radiation.
Relying solely on color to identify minerals can be the least useful method, as many minerals can have similar colors but different compositions. This can lead to misidentification and confusion.
You have more useful info than the British had clooines pre-WWII.
Recently scientists have become interested in the unique slime that hagfish produce and that research will probably lead to some new technology, so yes the jawless fish are useful to man.