An unknown substance has hydrogen ion concentration of [h+]=3.1*10^-8m. find the ph and classify the substance as acidic or basic

pH = 7.51. The substance is basic.

[H⁺] = 3.1 × 10⁻⁸ mol·L⁻¹.

pH = -log[H⁺] = -log(3.1 × 10⁻⁸) = 7.51

The substance is basic because pH > 7.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but