What can a emerald be described as

What is an example of a physical change in weight

Round 51.32975248 to the requested number of significant figure a. 2 significant figures 5 c. 6 significant figures b. S significant figures d. 7 significant figures

Part b calculate the enthalpy change, δh∘, for the "expansion" of methane: ch4 (g) →c (g) + 4h (g) express your answer to one decimal place and include the appropriate units.

Given the electronegativities below, which covalent single bond is most polar? Element: H C N O Electronegativity: 2.1 2.5 3.0 3.5 A) N-H B) O-C C) O-N D) C-H E) O-H

Sometimes when performing a crystallization, one solvent alone will not work and you have to use a solvent-pair. will the solvent pair pentaine and water work? why or why not?

Identify the spectator ions in the following complete ionic equation. 2k (aq) s2 - (aq) pb2 (aq) 2no-3 (aq) →pbs (s) 2k (aq) 2no-3 (aq) express your answers as ions separated by a comma.

4. A bird left its post and flew in a triangular path. It flew 21 yards south, 72 yards east and 75 yards diagonally to end back at the post. Is it a right triangle?

Condension occurs in the inside of your windows in Winters, why?

How can you use Hess's law to determine a reaction's enthalpy?

7. How much energy in KJ is released when 15.0 g of steam at 100.0 degrees Celsius is condensed and then frozen to ice at 0.0 degrees Celsius?