2. Look at the chemical formula of a compound below. Use the periodic table to answer the following question.
NH4
Which elements are found in this compound? (6.5A)
F. Nitrogen and Hydrogen
G. Nitrogen and Helium
H. Nickel and Hydrogen
J. Nickel and Helium

Which of the following natural processes is most likely to support the formation of an underwater sinkhole? a pollution buildup from deposited minerals b limestone cave collapsing due to changes in sea level c erosion of large amounts of sand moved by ocean waves d oxidation of rock formed by chemical weathering

Element j is 1s 2s 2p 3s . (i) how many unpaired electrons does j have? (ii) is j a good oxidizing agent or a reducing agent? (iii) state reason for the answer.

The most common form of matter in the universe