Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The correct answer is C: Speeds up the reaction. A catalyst works by providing an alternative pathway for the reaction to occur with lower activation energy, thus increasing the reaction rate without being consumed in the process. This is achieved by stabilizing the transition state of the reaction, making it easier for the reactants to form products. Choice A is incorrect because a catalyst does not slow down the reaction. Choice B is incorrect as catalysts do have a significant effect on reaction rates. Choice D is incorrect because a catalyst does not stop the reaction; it only affects the rate at which the reaction occurs.

Correct Answer: B

Rationale: The correct answer is B: Alpha. Alpha radiation involves the emission of helium ions, which are essentially helium atoms that have lost two electrons. This type of radiation consists of alpha particles, which are positively charged and relatively heavy. They have low penetration power and can be stopped by a sheet of paper or human skin. Beta radiation (choice A) involves the emission of high-energy electrons or positrons, not helium ions. Gamma radiation (choice C) consists of electromagnetic waves and does not involve the emission of particles. There is no radiation type known as Delta (choice D). Therefore, the correct answer is B as it accurately describes the characteristics of alpha radiation.

Correct Answer: B

Rationale: The correct answer is B: 0. Noble gases have a full outer electron shell, making them stable and unreactive. This full shell means they do not gain or lose electrons, so they have no overall charge, making their charge 0. Choice A (-1) is incorrect because it indicates gaining an electron to achieve a full outer shell, which is not characteristic of noble gases. Choices C (1) and D (2) are incorrect as they suggest a positive charge, which noble gases do not possess due to their stable electron configuration.

Correct Answer: A

Rationale: The correct answer is A: Unequal sharing of electrons. In a covalent bond, when two different atoms with different electronegativities come together, one atom attracts the shared electrons more strongly than the other, leading to an uneven distribution of electron density. This results in a dipole moment where one end of the bond is slightly positive and the other slightly negative. Choices B, C, and D are incorrect because in covalent bonds, electrons are not fully transferred or exchanged, but rather shared between atoms, leading to the creation of a dipole due to the unequal sharing of electrons.

Correct Answer: A

Rationale: The correct answer is A: Polar. In a covalent bond, if electrons are not shared equally, the bond is considered polar. This occurs when one atom has a higher electronegativity than the other, leading to an uneven distribution of electron density. As a result, one end of the bond will have a partial negative charge while the other end will have a partial positive charge, creating a dipole moment. Choices B (Non-polar) and D (Hydrogen) are incorrect because they do not specifically address the unequal sharing of electrons in a covalent bond. Choice C (Ionic) is incorrect as ionic bonds involve the complete transfer of electrons, not sharing.