how to determine the aspects for core and valence electrons in a periodic table. How comes in some elements like cobalt the 3d is on the valence side and arsenic the 3d is on the core side.​

Calculate - analysis of compound composed of iron and oxygen yields 174.86 of fe and 75.14g of o. what is the empirical formula for this compound?

Polar bears give birth and hunt on sea ice. which of the following would polar bears survive during the melting of arctic ice? growing another layer of fur during summer migrate inland to search for different food sources staying put until the ice refreezes sticking to the usual diet of seals

Detrimental the length of the object shown 1. 97.8mm 2. 97.80 mm 3. 97mm 4. 98mm