BMAT 2019 Section 2 Q10

[Nicolas Sanchez]

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Consider the non-radioactive elements in Group 1.
Which of the following statements is/are correct about the element with the largest atomic number?

1 It has the most vigorous reaction with cold water.
2 Its atom has the same number of electrons in its highest occupied energy level as other members of the group.

3 It is the most readily oxidised.

A. none of them
B. 1 only
C. 2 only
D. 3 only
E. 1 and 2 only
F. 1 and 3 only
G. 2 and 3 only
H. 1, 2 and 3

Jump to the accepted answer

[Paris Pitsinikos]

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Group 1 is the group of the alkali metals. The reactivity trend in the group increases from top to bottom. Therefore, the element found at the bottom of the group, which is also the element with the largest atomic number in the group, is the more reactive.

1. All alkali metals react aggressively with water. The fact that it is also the most reactive of the group, makes its reaction with water the most vigorous. This is correct.

2. The largest atomic number equals the largest number of electrons. The more electrons, the higher the energy levels of the shells they will occupy. This is correct.

3. It is the most reactive. Also, it has an oxidation number of +1 since it belongs to the alkali metals. So, it is the most readily oxidised. This is correct.

The answer is H.