Calculate the ph of a mixture made by adding 50.0 ml of 0.20 m hcl(aq) to 150.0 ml of water if the temperature of the mixture is 25.0 °c.

PH scale is used to determine how acidic or basic a solution is,
pH can be calculated once the [H⁺] is known.
Here HCl is a strong acid therefore it completely dissociates into H⁺ ions and Cl⁻ ions.
Therefore [HCl] = [H⁺]
number of HCl moles added - 0.20 mol/L x 0.050 L = 0.010 mol
The volume of the final solution = 50.0 + 150.0 = 200.0 mL
then the concentration of HCl = 0.010 mol / 0.200 mL = 0.05 mol/L
therefore [H⁺] = 0.05 M
then pH can be calculated using the following formula,
pH = -log[H⁺]
pH = -log(0.05 M)
pH = 1.30

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

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.