Visit the website 123iitjee.manishverma.site for latest posts, courses, admission & more.

### Complete combustion of 750 g of an organic compound ....

Complete combustion of 750 g of an organic compound provides 420 g of $CO_2$ and 210 g of $H_2 O$. The percentage composition of carbon and hydrogen in organic compound is 15.3 and _ _ _ _ respectively. (Round off to the nearest integer)

Solution

${n_{{H_2}O}} = \frac{{210}}{{18}} = \frac{{35}}{3}$

${n_H} = 2 \times {n_{{H_2}O}} = 2 \times \frac{{35}}{3} = \frac{{70}}{3}$

${m_H} = 1 \times \frac{{70}}{3}g$

% of H $= \frac{{70 \times 100}}{{3 \times 750}} = 3.11\% \approx 3\%$

### Sum of the coefficients in the expansion of $(x+y)^n$ ....
If the sum of the coefficients in the expansion of $(x+y)^n$ is 4096, then the greatest coefficient in the expansion is _ _ _ _ . Solution $C_0 + C_1 + C_2 + C_3 + ......................... + C_n =4096$ $\therefore 2^n = 4096 =2^{12}$ $\Rightarrow n = 12$ Greatest coefficient = ${}^{12}{C_6} = 924$