Infinite
Just count them - there are not THAT many of them.
Six
Five.
There are 18.
iron is 7.9 times greater than water
You can't do it from this information. You don't know if it is made from elements or compounds, and the density of a compound has nothing to do with that of its elements. Even if you do know it's made from elements there are far too many possible combinations.
calcium
it bonds with many elements but it is less reactive than the rest of the halogens
Many metals such as iron, lead, and gold have a greater density than water and will sink when placed in water. Other examples include platinum, mercury, and uranium.
The question cannot be answered because is does not specify great than what or less than what. Greater then -5 and less then -5 make no sense.
The prime numbers that are greater than 80 and less than 100 are 83, 89, and 97.
Twelve numbers exactly are greater than 76 and less than 89.
Infinitely many.
Trans-uranium elements are synthetic elements with atomic numbers greater than uranium (92). These elements are produced in laboratories through nuclear reactions and are typically radioactive with short half-lives. Many trans-uranium elements are involved in research and nuclear applications.
There are 15 composite numbers greater than 50 but less than 70
3 composite numbers, 21, 22, and 24, are greater than 20 but less than 25.