A chemical that donates a proton (hydrogen ion) is called
- A.Hydrophilic
- B.Protophilic
- C.Hydrophobic
- D.Acid
Correct answer
Explanation
The correct answer is D, Acid. In the Brønsted–Lowry theory an acid is any substance that gives away a proton, that is a hydrogen ion (H⁺), to another substance. A base is the partner that accepts that proton. When hydrochloric acid dissolves in water, for example, it hands its H⁺ to a water molecule and forms the hydronium ion, which is why the solution turns blue litmus red and has a pH below 7. The older Arrhenius idea says the same thing in water: an acid releases H⁺ ions, a base releases OH⁻ ions. Option A is wrong because hydrophilic means 'water-loving', a substance that mixes with or attracts water. Option B is wrong because protophilic means 'proton-loving', which describes a proton acceptor, the opposite of a donor. Option C is wrong because hydrophobic means 'water-fearing', a substance such as oil that repels water. Exam tip: acid = proton donor, base = proton acceptor (Brønsted–Lowry).
Practice Questions
View allWhich one of the following is monatomic?
- A.Hydrogen
- B.Sulphur
- C.Phosphorus
- D.Helium
Show answer
A monatomic element exists as single, separate atoms. Helium is a noble gas of group 18: its only shell, the first, is full with two electrons, so a helium atom has no tendency to share or transfer electrons and does not bond even with another helium atom.
Read the full explanation →The normal systolic pressure in human beings is :
- A.80 mm of Hg
- B.100 mm of Hg
- C.120 mm of Hg
- D.140 mm of Hg
Show answer
Blood pressure is written as two numbers, and normal adult blood pressure is about 120/80 mm of mercury.
Read the full explanation →'Study of human societies and cultures from the oldest times to the present' is the work of
- A.Archaeologists
- B.Anthropologists
- C.Palaeontologists
- D.Geologists
Show answer
Anthropology, from the Greek 'anthropos' (human) and 'logos' (study), is the science of human beings: how societies and cultures began, how they changed and how people live today.
Read the full explanation →Which of the following catalytic systems is used for the reduction of unsaturated hydrocarbon to saturated hydrocarbon?
- A.Copper and H2
- B.Iron and H2
- C.Zinc and H2
- D.Nickel and H2
Show answer
Adding hydrogen across the double or triple bond of an alkene or alkyne turns it into a saturated alkane; this reaction is called hydrogenation and it needs a catalyst.
Read the full explanation →Which one among the following is not a plant hormone ?
- A.Gibberellins
- B.Abscisic acid
- C.Auxins
- D.Thyroxine
Show answer
Thyroxine is an animal hormone, made by the thyroid gland in the neck, and it controls the rate of metabolism in the human body.
Read the full explanation →