Which of the following substances is/are mixture(s)?   

What criteria are most important to consider when small, charged particles approach one another? Mass Charge of particles Distance between particles Number of particles

A student is trying to construct an argument to support the following claim “particles in the atom are negatively charged”. What experiment and reasoning below would best assist the student with making their argument. Experiment: Cathode ray tube Gold foil Reasoning: It showed a bend in the beam of particles could occur when emitted. It showed that electrons were emitted from the atom regardless of the metal used. It showed that there was something small and positively charged in the middle of the atom that deflected a small number of particles that were passing through the atom. It showed that all atoms emit the same beam of particles regardless of the source of alpha particles.

A student is trying to construct an argument to support the following claim “that all atoms have electrons”. What experiment and reasoning below would best assist the student with making their argument. Experiment: Cathode ray tube Gold foil Reasoning: It showed that a bend in the beam of particles could occur when emitted. It showed that electrons were emitted from the atom regardless of the metal used. It showed that there was something small and positively charged in the middle of the atom that deflected a small number of particles that were passing through the atom. It showed that all atoms emit the same beam of particles regardless of the source of alpha particles.

Using the image below to determine which of the following statements is/are true. Substance A represents molecular compounds Substance B represents atoms of an element Substance C represents molecular compounds 

Which statement is true about 10.0 g of nitrogen gas (N2) and 10.0 g of water (H2O)?

Free Response 1  The element krypton (Kr) is used in lighting, photography, and fluorescent lamps. Kr has a melting point of -157 oC and boiling point of -153 o Part A. Please show Kr and its interactions at -155 oC and -50 oC.  Please label all interactions (ie. London dispersion forces and/or covalent bonds) at each temperature and label the states of matter. Be sure to include a key. Part B. Please explain, using your understanding of forces and energy, what is happening on the molecular level as Kr is heated from –155 oC to -50 oC as shown in Part A.  (Use 1-2 sentences)

Which of the following substances is/are mixture(s)?

Consider the following (hypothetical) protein that is composed of two short polypeptide chains that are connected by a disulfide bond (indicated by the vertical line): We have four identical aqueous solutions of the protein at pH 7. To solution #1 we add nothing. To solution #2 we add dithiothreitol (DTT). To solution #3 we add a protease that cuts peptide bonds immediately after (i.e. at the C-terminal side of) amino acids that have sidechains that are positively charged at pH 7. To solution #4 we add BOTH dithiothreitol AND the same protease used in #3. We then perform a SDS-PAGE experiment on all four solutions, but instead of adding Coomassie Blue, we use primary and secondary antibodies to perform an immunoblot (Western blot), the results of which are shown below. Based on the bands shown, select the part of the protein sequence that is most likely to be recognized by the primary antibody used in the immunoblot. You will want to use the size markers provided on the left-hand side of the gel. Assume also, for the purposes of this question, that each polypeptide moves on the gel at a rate that depends only on its number of residues. 

A change in chromosome structure that does not involve a change in the total amount of genetic material is: