Question

Subtract the sum of all prime numbers betweeb 10 and20 frm the sum off all composite numbers between 10 and 20?

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Answer 1

Answer:

All prime numbers between 10 and 20 :

11, 13, 17, 19

All composite numbers between 10 and 20 :

12, 14, 15, 16, 18

SUM of prime no.'s

11+13+17+19 = 60

SUM of composite numbers

12+14+15+16+18 = 75

NOW, Difference of sum of prime numbers from the sum of composite numbers

75-60

= 15

Answer 2

Step-by-step explanation:

CaCO3 + 2HCl -----> CaCl2 + H2O + CO2.

2.5g? g

Mass of CaCO3= 40+12+3(16)=52+ 48= 100.

Molar mass of CaCO3=100g.

Mass of CaCl2= 40 + 2(35.5)= 40+ 71= 111.

Molar mass of CaCl2=111g.

Mass of CaCO3 (g) Mass of CaCl2 (g)

For 100g of CaCO

3

, 111g of CaCl_2$$ is formed.

let for 2.5g of CaCO

3

, x g of CaCl

2

is formed.

Thus, by cross multiplication,

x=111×2.5/100=2.775g=2.78g.