How many joules of energy is required to raise the temperature of a 15.0 g sample of iron from 25.0 °C to 45.5 °C?  Hint: The specific heat of iron is 0.450 J/g-K.

In which of the following does the central atom have ONE nonbonding electron pair (lone pair) on the central atom? 

You wish to make 125.0 mL of a 0.125 M solution of KNO3. What volume (in mL) of 1.50 M solution of KNO3 is required to make this solution?

You wish to make 200.0 mL of a 0.150 M solution of K2CrO4. What volume (in mL) of 2.00 M solution of K2CrO4 is required to make this solution?

Which of the below statements is true regarding homeostasis in living things? a. Only multicellular organisms need to maintain homeostasis. b. Only single celled organisms need to maintain homeostasis. c. All living things need to maintain homeostasis. d. Photosynthetic organisms do not need to maintain homeostasis because they get their energy from the sun.

A 46.0 L sealed container of a mixture of 0.240 mol N2(g), 1.57 mol He(g), and 0.620 mol CH4(g) has a total pressure of 930 torr at a temperature of 282K.  What is the partial pressure of helium in this mixture.

The energy (in J) of a photon that has a frequency of 2.07 x 1016 Hz is _______________.

The energy (in J) of a photon that has a frequency of 3.53 x 1015 Hz is _______________.

For xenon difluoride (XeF2) molecule, the electron domain geometry (EDG) is              , the molecular geometry (MG) is              , and XeF2 molecule has an approximate bond angle of             .

Carbon dioxide gas (CO2) and Helium gas (He) start to effuse through a pinhole from a container. How much faster will He(g) effuse from the container than CO2(g)? Hint: The higher the effusion rate, the faster the gas effuses.