Chemistry : Percentage Composition of Chemical Compounds

What is the percentage of an element in each chemical compound whose formula is given below? Type only the number as your answer.
Given Atomic Weights:
H = 1 ; C = 12 ; N = 14 ; O = 16 ; Na = 23 ; Mg = 24 ; Al = 27 ; P = 31 ; S = 32 ;
Cl = 35.5 ; K = 39 ; Ca = 40; Cr = 52; Mn = 55 ; Fe = 56 ; Cu = 63.5 ; Zn = 65

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Multiple choice | Fill in the blanks | Match the Columns

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Enter in the box the number corresponding to the right answer
Percentage of Hydrogen [H] in Sodium hydroxide [NaOH]	Hint Hint	1	39

Percentage of Potassium [K] in Potassium bicarbonate [KHCO₃]	Hint	2	48

Percentage of Oxygen [O] in Potassium bicarbonate [KHCO₃]	Hint	3	60

Percentage of Magnesium [Mg] in Magnesium oxide [MgO]	Hint	4	2.5

Percentage of Calcium [Ca] in Calcium carbonate [CaCO₃]	Hint	5	40

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