Chemistry Flashcards

Which gas law states that the volume of a gas at constant temperature is inversely proportional to its pressure?

Answer: Boyle's Law

Boyle's Law (P₁V₁ = P₂V₂) states that pressure and volume are inversely proportional at constant temperature.

Which element is a metalloid (semimetal) on the periodic table?

Answer: Silicon

Silicon (Si) is a metalloid with properties intermediate between metals and nonmetals, widely used as a semiconductor.

What is the correct name for the compound Fe₂O₃?

Answer: Iron(III) oxide

In Fe₂O₃, iron has an oxidation state of +3 (since 3 oxygens at -2 = -6, balanced by 2 Fe at +3 = +6), so it is iron(III) oxide.

Which quantum number describes the shape of an electron's orbital?

Answer: Angular momentum quantum number (l)

The angular momentum quantum number (l) defines the shape of an orbital: l=0 is s (spherical), l=1 is p (dumbbell), l=2 is d, etc.

In an electrochemical cell, oxidation occurs at the:

Answer: Anode

Oxidation (loss of electrons) always occurs at the anode in both galvanic and electrolytic cells.

Which of the following represents a conjugate acid-base pair?

Answer: NH₃ and NH₄⁺

NH₃ and NH₄⁺ differ by exactly one proton (H⁺), making them a conjugate acid-base pair (NH₃ is the base, NH₄⁺ is its conjugate acid).

What is the percent composition by mass of hydrogen in H₂O?

Answer: 11.1%

H₂O has molar mass 18 g/mol; hydrogen contributes 2 g/mol, so percent = (2/18) × 100 ≈ 11.1%.