$3.011 \times 10^{22}$ atoms of an element weigh $1.15 \ g$. The atomic mass of the element is: (in $amu$)

$4 \, g$ of copper is dissolved in concentrated $HNO_3$. Upon strong heating of the resulting copper nitrate solution,$5 \, g$ of its oxide is obtained. The equivalent weight of copper is ...... .

Which method is used to determine atomic mass accurately?

One atomic mass unit $(amu)$ is equal to:

Chlorine has two isotopes $^{37}Cl$ and $^{35}Cl$ with percentage abundance of $25\%$ and $75\%$ respectively. Find the average atomic mass of chlorine.

The equivalent mass of an element $X$ is $9$. If the vapor density of its chloride salt is $66.75$,determine the valency of element $X$.