Which of the following is a true statement about acids and bases -an acid has a ph of 7.1 -an acid accord hydrogen ions -a base has ph of 7 -a base gives off hydroxide ions

According to Arrhenius  concept:

An Acid is a substance which gives hydrogen ions (H⁺) when dissolve in water. Examples are HCl (Hydrochloric acid) ,  HNO₃ ( Nitric acid)

                     HCl H⁺ + Cl⁻

A base is a substance which gives hydroxide ions (OH⁻) when dissolved in water. Examples are  NaOH (Sodium hydroxide), KOH (Potassium hydroxide)

                      NaOH Na⁺ + OH⁻

micro/nanoscale topography surface exhibits many prominent properties and is extensively employed in biomedical device, microfluidic device and energy device fabrication. additionally, the clinical applications of biomaterials can be largely expanded with of nanostructured surfaces.

a chair, a bed, and a toothbrush

explanation:

i was told this before by a teacher, so yeah