Question

The atomic weight of two elements A and B are 40 and 80 respectively. If $xg$ of A contains y atoms,how many atoms are present in $2xg$ of B?

• A. $\frac{y}{2}$
• B. $\frac{y}{4}$
• C. $y$
• D. $2y$

Answer 1

The correct option is C

$y$

Number of moles of A = $\frac{x}{40}$

Number of atoms of A = $\frac{x}{40}\times Avogadrono.=y$ (say)

Or $x$ = $\frac{40y}{Avogardono.}$

Number of moles of B= $\frac{2x}{80}$

Number of atoms of B= $\frac{2x}{80}\times Avogadrono.$

= $\frac{2x}{80}$$\times$$\frac{40y}{Avogardono}\times Avogadrono.=y$