The half life of protactinium 234 in its ground state is 6.69 h. What fraction of a given amount remains after 26.76 h

A 140-lb person burns about 2500 Calories to run a marathon. Part A How much energy is burned in kJ? Assume two significant figures.

2 Mg (s) + CO2 (g)  2 MgO (s) + C (s) What mass solid magnesium is req'd to react w/250 mL carbon dioxide at 1.5 atm and 77oC to produce solid magnesium oxide and solid carbon? a 6.3 g b 0.36 g c 3.6 g d 0.63 g

What is the easiest way to do mole conversions i. e. to grams, molecules, and formula units?

Which bases can deprotonate acetylene? the pka values of the conjugate acids are given in parentheses. select all that apply. ch3ch2s - (pka = 10.5) ch2═ch - (pka = 44) ch3nh - (pka = 40) ch3ch2o - (pka = 16) ?

Mrs. Jones is pushing her daughter in a stroller. If the stroller has a mass of 5 kg and it is accelerating at 2 m/s2, what amount of force is Mrs. Jones applying to the stroller? N (free response)

Which of the following best describes what causes the phases of the moon? The alignment of the sun, Earth, and moon The speed of the moon around the Earth The speed of the Earth around the sun The alignment of the planets

At which temperature would atoms of a He (g) sample have the greatest average kinetic energy? (1) 25°C (3) 273 K (2) 37°C (4) 298 K

In the reaction, HCl + H2O produces H3O + Cl, what is the conjugate acid

Draw the curved arrow mechanism for the conversion of aniline into benzenediazonium ion, and draw the final product that forms after the benzenediazonium ion is treated with

Sodium chloride is stirred into water to form a solution. in this case, what are sodium chloride and the water?