Question

Three elements A, B, C have atomic numbers 4, 12 and
19 respectively.
(i) Which of the two elements are having the same
number of valence electrons?
(ii) What is the electronic configuration of the other
element?

Answer 1

Explanation:

Element A, Atomic number =12 which is Magnesium Mg

Electronic configuration is 1s

2

2s

2

2p

6

3s

2

On the basis of electronic configuration last electron enters in s−block, so it is s−block element.

Element B, Atomic number= 19 which is Potassium K

configuration=1s

2

2s

2

2p

6

3s

2

3p

6

4s

1

On the basis of electronic configuration last electron enters in s−block, so it is s−block element.

Element C, Atomic number= 29 which is CopperCu

configuration=1s

2

2s

2

2p

6

3s

2

3p

6

4s

1

3d

10

On the basis of electronic configuration last electron enters in d−block, so it is d−block element. Due to extra stability of half filled and full filled orbital one electron from s shifts to d subshell.

Element D, Atomic number= 36 which is KryptonKr

configuration=[Ar] 3d

10

4s

2

4p

6

On the basis of electronic configuration last electron enters in p−block, so it is p−block element.

Answer 2

Answer:

say kid amogus backwards

Explanation: