Chemistry Flashcards
7 cards from real Regents practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Chemistry flashcards as text
Which of the following describes a chemical property of iron?
Answer: Iron reacts with oxygen to form rust
The ability to rust (react with O₂ and H₂O to form Fe₂O₃·nH₂O) is a chemical property because it involves a change in chemical composition.
According to Le Chatelier's Principle, increasing pressure on a gaseous equilibrium shifts the reaction toward:
Answer: The side with fewer moles of gas
Increasing pressure shifts equilibrium toward the side that reduces pressure, which is the side with fewer moles of gas.
What type of isomers have the same molecular formula and connectivity but differ in the spatial arrangement of atoms?
Answer: Stereoisomers
Stereoisomers (including enantiomers and diastereomers) share the same molecular formula and bond connectivity but differ in three-dimensional arrangement.
Which of the following solutions is the most concentrated?
Answer: 2.0 M NaCl
Molarity (M) measures moles of solute per liter of solution; 2.0 M has the most moles of NaCl per liter and is therefore most concentrated.
What is the half-life of a radioactive isotope if 75% of a sample decays in 20 years?
Answer: 10 years
After one half-life, 50% remains; after two half-lives, 25% remains (75% decayed). Two half-lives = 20 years, so one half-life = 10 years.
Which property increases as you move down a group on the periodic table?
Answer: Atomic radius
Atomic radius increases down a group because each successive element has an additional electron shell, increasing distance from the nucleus.
A buffer solution resists changes in pH because it contains:
Answer: A weak acid and its conjugate base
A buffer consists of a weak acid and its conjugate base (or weak base and conjugate acid), which can neutralize added acids or bases.