Which of the following is not a possible sublevel?
1s
2d
3p
4f

The sub-level that is not possible is 2d.

The values of the subsidiary quantum number (l) must range from 0 to (n - 1). This means that sub - levels in which n = l are not allowed

Recall that s p d f corresponds to 0 1 2 3. So the d orbital has l =2.

Having a 2d  sub - level implies a violation of the rule because n = l which is not allowed.

As a result of this, the 2d sub - level does not exist.

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2d

Explanation:

That is supposed to be 3d. According to the Periodic Table of Elements there are four blocks:

- s block: Alkali Metals and Alkaline Earth Metals [Groups 1 and 2]

- p block: Groups 13 to 18 [including Halogens in Group 17 and Noble Gasses in Group 18]

- d block: Transition Metals, NOT INCLUDING the Actinide and Lanthanide Series [Lanthanide → Atomic Number 57 (Lanthanum) to 70 (Ytterbium); Actinide → Atomic Number 89 (Actinium) to 102 (Nobelium)]

- f block: Actinide and Lanthanide Series [located towards the very bottom of the table to keep the table from being so wide]

** - g block: Hypothetical block of elements, whose outermost electrons are posited to have one or more g-orbital electrons, but no p, d, or f-orbital electrons.

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a is the answer to this question

explanation:

3 1/4 %

explanation: