Why are elements sometimes called pure

Calculate the concentration of hydronium in a solution that contains 5.5x10-5 M OH - at 25C. Indentify the solution as acidic, basic, or neutral.

Which of the following is true about science? Select one: a. It is not influenced by social conditions. b. It is not determined by external local factors. c. Political conditions are unable to influence it. d.

Five graduate students prepare extracts from 5 different tissues. Each student measures the total amount of alcohol dehydrogenase and the total amount of protein in his or her extract.

Which element has no stable isotopes? 1. CO27 2. Sb51 3. TH90 4. Pb82

Find the radius (r) of an aluminum cylinder that is 2.40 cm long and has a mass of 13.0 g . For a cylinder, V=π r 2 l . (The density of aluminum is 2.70 g/c m 3 .)

Two members of the Boron family owe their names to bright lines in their emission spectra. Indium has a bright indigo blue line (451.1nm) and Thallium has a bright green line (535.0 nm). What are the energies of these two spectra lines?

Whats the answer to 7/2 * 1/5?

Which statement correctly describes the relationship between reactant and yield? The actual yield is calculated from the amount of the excess reactant present. The actual yield is calculated from the amount of the limiting reactant present.

Balance the following reaction. Leave the box empty if no other coefficient is needed. C2H5 + O2 → CO2 + H2O

What three human body systems coordinate cause an arm to move