Which of the following has the highest ionization energy?
A. Mg
B. Na
C. Al
D. Si
Answer: Option D
Solution (By JKExamLibrary)
Ionization energy generally increases across a period due to increasing nuclear charge and decreasing atomic size. Among Na, Mg, Al, and Si (Period 3), Si has the highest effective nuclear charge and smallest size, thus requiring the maximum energy to remove the outermost electron from its gaseous state.
Assertion (A): A catalyst does not change the equilibrium yield of a reaction. Reason (R): A catalyst speeds up both the forward and backward reactions equally.
A.Both A and R are true and R is the correct explanation of A.
B.A is false but R is true.
C.A is true but R is false.
D.Both A and R are true but R is NOT the correct explanation of A.
Explanation:
A catalyst lowers the activation energy for both the forward and reverse reactions by the same amount. Therefore, it increases the rates of both reactions equally, allowing the system to reach equilibrium faster, but without changing the final equilibrium concentrations (yield). Both statements are correct and R explains A.
Consider the following statements: 1. A buffer solution resists changes in pH upon adding small amounts of acid or base. 2. A buffer is made of a strong acid and its conjugate base. Which is/are correct?
Explanation:
A buffer solution maintains a relatively constant pH when small amounts of strong acid or base are added. However, it is typically composed of a weak acid and its conjugate base (or a weak base and its conjugate acid). A strong acid completely dissociates and cannot form a buffer system. Thus, only statement 1 is correct.
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