Question

there are 2 defective screw in a box having 6 screws. in how many ways can 2 non-defective screws be selected from the box please answer correct me please​

Answer 1

Answer:

When identifying a rock you must first identify the individual minerals that make up that rock. ... Some characteristics, such as a mineral's hardness, are more useful for mineral identification. Color is readily observable and certainly obvious, but it is usually less reliable than other physical properties.