Question

$XgmA$ atoms on combining with $Y$ atoms of $B$ form $5$ molecules of a compound containing $A$ and $B$. Find the molecular weight of the compound formed. (Atomic weight of $B=M$).

• A. $\frac{(X{N}_A+MY)}{5}$
• B. $\frac{X+M}{5}$
• C. $\frac{X-M}{5}$
• D. $\left(\frac{X+MY{N}_A}{5}\right)$

Answer 1

The correct option is A $\frac{(X{N}_A+MY)}{5}$

Let us assume that,

Total mass of $A$ reacted $=X\times N_A$

Total mass of $B$ reacted $=Y\times Mgm$

$=numbersofatoms\times atomicweight$

Total mass of reactants $=X{N}_A+YMgm$

According to the law of conservation of mass,

Total mass of reactant = Total mass of product

$\therefore$ Mass of $5$ molecules formed $=X{N}_A+YM$

$\therefore$ Mass of $1$ molecule of given compound $=\frac{X{N}_A+YM}{5}$

$\therefore$ The correct option is $A$.