Answer:
C. BF₃
Chemistry Concepts:
Sodium hydroxide is a white, deliquescent, water-soluble liquid, NaOH, usually in the form of lumps, sticks, chips, or pellets, that upon solution in water generates heat: used chiefly in the manufacture of other chemicals, rayon, film, soap, as a laboratory reagent, and in medicine as a caustic.
Calcium carbonate is a white, crystalline, water-insoluble, tasteless powder, CaCO3, occurring in nature in various forms, as calcite, chalks, and limestone: used chiefly in dentifrices and polishes and in the manufacture of lime and cement.
Boron trifluoride (BF3) is composed of a boron (B) atom bonded by three fluoride (F) atoms through single covalent bonds.
Ammonia is a colorless, pungent, suffocating, highly water-soluble, gaseous compound, NH3, usually produced by the direct combination of nitrogen and hydrogen gases; used chiefly for refrigeration and in the manufacture of commercial chemicals and laboratory reagents.
Sodium is a soft, silver-white, metallic element that oxidizes rapidly in moist air, occurring in nature only in the combined state, and use in the synthesis of sodium peroxide, sodium cyanide, and tetraethyllead: a necessary element in the body for the maintenance of normal fluid balance and other physiological functions. Symbol: Na; atomic weight: 22.9898; atomic number: 11; specific gravity: 0.97 at 20°C.
Oxygen is a colorless, odorless, gaseous element constituting about one-fifth of the atmosphere and present in a combined state in nature. it is the supporter of combustion in air and was the standard of atomic, combining, and molecular weights until 1961, when carbon 12 became the new standard; Symbol: )O; atomic weight: 15.9994; atomic number: 8; density: 1.4290 g/l at 0°C and 760 mm pressure.
Hydrogen is a colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known elements. Symbol: H; atomic weight: 1.00797; atomic number: 1; density: 0.0899 g/l at 0°C and 760 mm pressure.
Calcium is a silver-white divalent metal, occurring combined in limestone, chalk, gypsum, etc., occurring also in vertebrates and other animals, as a component of the bone, skeletal mass, shell, etc. and as a necessary element in the nerve conduction, heartbeat, muscle contraction, and many other physiological functions. Symbol: Ca; atomic weight: 40.08; atomic number: 20; specific gravity: 1.55 at 20°C.
Carbon is a widely distributed element that forms organic compounds in combination with hydrogen, oxygen, etc., and that occurs in a pure state as diamond and graphite, and in an impure state as charcoal. Symbol: C; atomic weight: 12.011; atomic number: 6; specific gravity (of diamond) 3.61 at 20°c; (of graphite) 2.26 at 20°C.
Boron is a nonmetallic element occurring naturally only in combination, as in borax or boric acid, and obtained in either an amorphous or a crystalline form when reduced from its compounds. Symbol: B; atomic weight: 10.811; atomic number: 5.
Fluorine is the most reactive nonmetallic element, a pale-yellow, corrosive, toxic gas that occurs combined, especially in fluorite, cryolite, phosphate rock, and other minerals. Symbol F; atomic weight: 18.9984; atomic number: 9.
Nitrogen is a colorless, odorless, gaseous element that constitutes about four-fifths of the volume of the atmosphere and is present in combined form in animal and vegetable tissues, especially in proteins: used chiefly in the manufacture of ammonia, nitric acid, cyanide, explosives, fertilizer, dyes, as a cooling agent, etc. Symbol: N; atomic weight: 14.0067; atomic number: 7; density: 1.2506 g/l at 0°C and 760 mm pressure.
Among the given options, the compound that represents a Lewis acid is option C: BF₃ (Boron trifluoride).
In Lewis acid-base theory, a Lewis acid is a molecule or ion that can accept a pair of electrons (an electron pair acceptor). Boron trifluoride (BF₃) is a compound where boron acts as a Lewis acid. It has an empty orbital and can accept a pair of electrons from a Lewis base.
The other options mentioned are:
- a. NaOH: Sodium hydroxide is a strong base and does not act as a Lewis acid.
- b. CaCO₃: Calcium carbonate is a compound and does not act as a Lewis acid.
- d. NH₃: Ammonia is a Lewis base as it can donate a pair of electrons, not a Lewis acid.
Therefore, the correct answer is option C: BF₃ (Boron trifluoride).