Question

1. As you move across the Periodic Table, reactivity with H₂O varies. For example, when [Element A] is placed in H₂O, it [Result A]. On the other hand, [Element B] when it's placed in H₂O [Result B].

A) [Element A: a non-metal]; [Result A: doesn't react]; [Element B: a metal]; [Result B: reacts vigorously].
B) [Element A: a metal]; [Result A: reacts vigorously]; [Element B: a non-metal]; [Result B: doesn't react].
C) [Element A: a noble gas]; [Result A: reacts violently]; [Element B: an alkali metal]; [Result B: reacts mildly].
D) [Element A: a transition metal]; [Result A: explodes]; [Element B: a halogen]; [Result B: remains inert].
2. As you move down the Periodic Table, reactivity with H₂O also varies. For example, when [Element C] is placed in H₂O, it [Result C]. On the other hand, [Element D] when it's placed in H₂O [Result D].

A) [Element C: a non-metal]; [Result C: doesn't react]; [Element D: a metal]; [Result D: reacts vigorously].
B) [Element C: a metal]; [Result C: reacts vigorously]; [Element D: a non-metal]; [Result D: doesn't react].
C) [Element C: a noble gas]; [Result C: reacts violently]; [Element D: an alkali metal]; [Result D: reacts mildly].
D) [Element C: a transition metal]; [Result C: explodes]; [Element D: a halogen]; [Result D: remains inert].

Answer 1

Across the Periodic Table, a metal reacts vigorously with water while a non-metal does not; as you descend the table, reactivity generally increases. For example, sodium (a metal) reacts vigorously, whereas carbon (a non-metal) does not. Similarly, lithium reacts more explosively with water compared to sodium as you move down the group.

Step-by-step explanation:

The reactivity of elements with water varies across and down the Periodic Table. Reactivity is influenced by an element's position in the activity series, which dictates how elements replace others in single-replacement reactions. For the first question, the correct option is (B) wherein Element A is a metal that reacts vigorously with water, and Element B is a non-metal that doesn't react. A typical example of this is sodium, a metal, which reacts vigorously with water, and carbon, a non-metal, which does not react with water.

As for the second question, elements that are more reactive, as you move down a group, typically react more vigorously with water. Transition metals can react in various ways depending on their position in the activity series, but generally, they do not explode upon contact with water. Therefore, both options (A) and (B) seem correct; however, option (A) is more commonly encountered in the classroom. Thus, Element C, a metal, reacts vigorously as you move down the group in the Periodic Table, and Element D, a non-metal, tends not to react with water. For instance, lithium reacts more explosively than sodium with water.