A642 ml sample of oxygen gas at 23.5°c and 795 mm hg, is heated to 31.7°c and the volume of the gas expands to 957 ml. what is the new pressure in atm?

Let's assume that O₂ is an ideal gas.

We can use combined gas law,
 PV/T = k (constant)

Where, P is the pressure of the gas, V is volume of the gas and T is the temperature of the gas in Kelvin.

For two situations, we can use that as,
P₁V₁/T₁= P₂V₂/T₂

P₁ = 795 mm Hg
V₁ =  642 mL
T₁ = (273 + 23.5) K = 296.5 K
P₂ = ?
V₂ = 957 mL
T₂ = (273 + 31.7) K = 304.7 K

By applying the formula,

795 mm Hg x 642 mL / 296.5 K = P₂ x 957 mL / 304.7 K
                                              P₂ = 548.07 mm Hg
                                              P₂ = 548 mm Hg
760 mmHg = 1 atm
548 mm Hg = 1 atm x (548 mmHg / 760 mmHg) = 0.721 atm

Pressure of gas = 548 mm Hg = 0.721 atm

Distance and velocity graph

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.