Determine the group, period and block in which each of the following elements is located in the Periodic Table: 1. [He] 2s1
2. [Ne] 3s2

Calculate the change in entropy if br2(l) is converted into gaseous br atoms. s° for br2(l) = 152.2 j/(mol•k) s° for br2(g) = 245.5 j/(mol•k) s° for br(g) = 175.0 j/(mol•k)

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a.the mitochondria b.the nucleus c.the vacuoles d.the endoplasmic reticulum