Which of the following shows a balanced equation?  Place your letter answer here. A) Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + P4(s)   B) Ca3(PO4)2(s) + 3SiO2(s) + 14C(s) → 3CaSiO3(s) + 14CO(g) + P4(s)   C) Ca3(PO4)2(s) + 3SiO2(s) + 8C(s) → 3CaSiO3(s) + 8CO(g) + 2P4(s)   D) 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + P4(s)   E) 2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) → 6CaSiO3(s) + 10CO(g) + 4P4(s)  

Given that  the atoms X, Y, Z, and R have the nuclear compositions listed below, which two of those shown are isotopes?  

Jennifer learns that the price of CDs will be going up 10% next week.  She usually buys three CDs per week.  What happens to Jennifer’s demand for CDs this week?

Draw the Lewis structure for the molecule CH2CHCH3. How many sigma and pi bonds does it contain? A) 8 sigma, 1 pi B) 9 sigma, 0 pi C) 9 sigma, 1 pi D) 7 sigma, 2 pi E) 8 sigma, 2 pi

Consider the statements below and select the best one.  

Two students determine the percentage of lead in a sample as a laboratory exercise.  The true percentage is 22.50%.  The students’ results for the three determinations are as follows:   Student A)  22.52%, 22.48%, 22.54% Student B)  22.64%, 22.58%, 22.62%   Which of the following statements represents the best analysis of the data?  

Which of the following elements has been chosen as the isotope standard in measuring atomic mass?  

Write the formula for copper (II) sulfate pentahydrate. A) Cu2SO3∙H5 B) Cu2S∙H2O C) CuS∙5H2O D) (CuSO4)5 E) CuSO4∙5H2O  

How many anions are there in  3.50 g of MgBr2? A) 1.14 × 1022anions B) 2.29 × 1022anions C) 3.17 × 1025anions D) 6.34 × 1025 anions

A)  Give an example of a scientific theory.  Complete sentences not needed. B)  Are theories considered facts?  State yes or no.