Question

element perfect mass no and valency upto 1 to 20

Answer 1

1) Hydrogen (H)

Atomic Number -- 1
Valency -- 1

2) Helium (He)

Atomic Number --2
Valency -- 0

3) Lithium (Le)

Atomic Number -- 3
Valency -- 1

4) Beryllium (Be)

Atomic Number -- 4
Valency -- 2

5) Boron (B)

Atomic Number-- 5
Valency -- 3

6)Carbon(C)
Atomic Number: 6
Valency = 4

7) Nitrogen (N)

Atomic Number --7
Valency --  3

8) Oxygen (O)

Atomic Number --8
Valency --2

9) Fluorine (F)

Atomic Number -- 9
Valency  --1

10) Neon (Ne)

Atomic Number -- 10
Valency -- 0

11)Sodium (Na)

Atomic Number --11
Valency -- 1

12) Magnesium (Mg)

Atomic Number -- 12
Valency -- 2

13) Aluminum (Al)

Atomic Number -- 13
Valency -- 3

14) Silicon (Si)

Atomic Number -- 14
Valency -- 4

15) Phosphorus (P)

Atomic Number -- 15
Valency -- 5 , 3

16) Sulfur (S)

Atomic Number -- 16
Valency -- 2

17) Chlorine (Cl)

Atomic Number -- 17
Valency -- 1

18) Argon (Ar)

Atomic Number -- 18
Valency -- 0

19) Potassium (K)

Atomic Number --19
Valency -- 1

20) Calcium (Ca)

Atomic Number -- 20
Valency -- 2

21) Scandium (Sc)

Atomic Number -- 21
Valency -- 3

22) Titanium (Ti)

Atomic Number --22
Valency -- 4

23) Vanadium (V)

Atomic Number --23
Valency -- 5 , 4

24) Chromium (Cr)

Atomic Number --24
Valency --  2

25) Manganese (Mn)

Atomic Number -- 25
Valency -- 7 , 4 , 2

26) Iron (Fe)

Atomic Number -- 26
Valency -- 2 , 3

27) Cobalt (Co)

Atomic Number -- 27
Valency -- 3 , 2

28) Nickel (Ni)

Atomic Number -- 28
Valency -- 2

29) Copper (Cu)

Atomic Number -- 29
Valency  -- 2 , 1

30 ) Zinc (Zn)

Atomic Number --30
Valency -- 2

Hope This Helps You!

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Answer 2

Hii Anu ✋
here's ur answer

➡1. Hydrogen - 1 - 1
2. Helium - 4 - 0
3.Lithium - 6 - 1
4. Berrylium - 9 - 2
5. boron - 10 - 3
6. carbon - 12 - 3
7. nitrogen - 14 - 2
8. oxygen - 16 - 1
9 fluorine - 18 - 0
10. Neon - 20 - 1
11. sodium -22 - 2
12.magnesium - 24 - 3
13. aluminium -26 - 3
14. silicon - 28 - 2
15. phosphorus - 30 - 1
16. sulphur - 32 - 0
17. chlorine -35 - 1
18.potassium -39 - 2
19. argon -39 - 3
20. calcium - 40 - 2

HOPE IT HELPS YOU.. ☺