Question

In an organic compound of molar mass greater than hundred containing only carbon hydrogen and nitrogen percentage of carbon 6 times the percentage of hydrogen will the sum of the percentage of carbon and hydrogen is 1.5 times the percentage of nitrogen what is the least molar mass​

Answer 1

Answer:105

Explanation:

Let the percentage mass of N = x%

percentage mass of C = y%

and percentage mass of H = z%

here, x + y + z = 100% .....(1)

a/c to question,

(y + z) = 1.5x

or, 2(y + z) = 3x

or, 2(100 - x) = 3x [ from equation (1), ]

or, 200 - 2x = 3x

or, x = 40 %

so, y + z = 60% ......(2)

find percentage mass ratio ,

N⇒40/14 = 2.85

C ⇒y/12

H ⇒ z/1

so, 2.85 : y/12 : z/1 ≈ 3 : y/12 : z/1

we have to assume y and z in such a way that molar mass doesn't less than 100.

if we assume , y = 48 then z = 60 - 48 = 12

so, then, 3 : 4 : 12

means, molecular formula will be

then, molar mass = 12 × 4 + 14 × 3 + 12

= 48 + 42 + 12

= 102g/mol. this is nearest value of 105g/mol. hence, option (c) is correct choice.

[ actually, here we are using hitandtrialmethod that's why answer is little different from actual answer]