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Questions in chemistry

[Done] Which of the following is considered to be a dangerous procedure in the laboratory setting? A. Pouring all liquids, especially acids and bases, over the sink B. Wearing goggles C. Pushing glass tubing, thermometers, or glass thistle tubes through a rubber cork D. Pointing the mouth of a test tube that is being heated away from you and others E. Knowing where the fire extinguisher and eyewash stations are located

[Done] In most of its compounds, this element exists as a monatomic cation. A. F B. S C. N D. Ca E. Cl

[Done] Used to deliver acids and bases in a titration: A. Calorimeter B. Geiger counter C. Burette D. Funnel E. Bunsen burner

[Done] Where does the blood pick up oxygen?

[Done] What are two conditions atoms must have in order to form covalent bonds with one another?

[Done] The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements. Can someone help me with this one? I dont understand that at all :(

[Done] Which formula represents an unsaturated hydrocarbon? Picture I How many pairs of electrons are shared between the two nitrogen atoms? Picture II I NEED EXPLANATION FOR BOTH QUESTIONS, PLEASE HELP ME! :)

[Done] 50 grams of acetic acid [tex]C_2H_4O_2[/tex] are dissolved in 200 grams of water. Calculate the weight percentage and mole fraction of the acetic acid in the solution.

[Done] Ammonium phosphate, [tex](NH_4)_3PO_4[/tex], is a strong electrolyte. What will be the concentration of all the ions in a 0.9 M solution of ammonium phosphate?

[Done] What is the oxidation number of Mn in [tex]$KMnO_4$[/tex]? A. -7 B. -3 C. 0 D. +3 E. +7