Equal weights of Zn metal and iodine are mixed together and $I_2$ is completely converted to$\mathrm{Z}\mathrm{n}{\mathrm{I}}_2$. What fraction by weight of original Zn remains unreacted? (Zn = 65, I = 127)

The ammonia is prepared by treating ammonium sulphate with calcium hydroxide is completely used by ${\mathrm{NiCl}}_2\mathbf{·}6{\mathrm{H}}_2\mathrm{O}$ to form a stable coordination compound. Assume that, both the reactions are $100\%$ completed. If $1584 \mathrm{g}$ of ammonium sulphate and $952 \mathrm{g}$ of ${\mathrm{NiCl}}_2\mathbf{·}6{\mathrm{H}}_2\mathrm{O}$ are used in the preparation, the combined weight (in grams) of gypsum and the nickel ammonia coordination compound produced is ____.

Atomic weights in $\mathrm{g}\mathrm{ }{\mathrm{mol}}^{-1}$:

$$\begin{gathered} \mathrm{H}=1;\mathrm{ }\mathrm{N}=14\mathrm{ } \\ \mathrm{O}=16; \mathrm{S}=32\mathrm{ } \\ \mathrm{Cl}=35.5;\mathrm{ }\mathrm{Ca}=40\mathrm{ } \\ \mathrm{Ni}=59 \end{gathered}$$

In the following reaction:

$\mathrm{A}+2\mathrm{B}+3\mathrm{C}\rightleftharpoons \mathrm{A}{\mathrm{B}}_2{\mathrm{C}}_3$
$6.0 \mathrm{g}$ of $\mathrm{A}$, $6.0\times {10}^{23}\mathrm{ }$ atoms of $\mathrm{B}$ and $0.036 \mathrm{mol}$ of $\mathrm{C}$ reacted and formed $4.8 \mathrm{g}$ of compound $\mathrm{A}{\mathrm{B}}_2{\mathrm{C}}_3$. If the atomic mass of $\mathrm{A}$  and $\mathrm{C}$ are $60$ and $80 \mathrm{amu}$, respectively. What is the atomic mass of $\mathrm{B}$ in $\mathrm{amu}$? (Avogadro number$=6\times {10}^{23}$)

${\mathrm{NaClO}}_3$ is used, even in spacecrafts, to produce ${\mathrm{O}}_2.$ The daily consumption of pure ${\mathrm{O}}_2$ by a person in $492 \mathrm{L}$ at $1$ atm, $300\mathrm{K}.$ How much amount of ${\mathrm{NaClO}}_3,$ in grams, is required to produce ${\mathrm{O}}_2$ for the daily consumption of a person at $1$ atm, $\mathrm{}300\mathrm{K}$ ? 

${\mathrm{NaClO}}_3\left(\mathrm{s}\right)+\mathrm{Fe}\left(\mathrm{s}\right)\to {\mathrm{O}}_2\left(\mathrm{g}\right)+\mathrm{NaCl}\left(\mathrm{s}\right)+\mathrm{FeO}\left(\mathrm{s}\right)$
$\mathrm{R}=0.082 \mathrm{L} \mathrm{atm} {\mathrm{mol}}^{-1} {\mathrm{K}}^{-1}$

Give answer to the nearest integer value.

A gaseous hydrocarbon on combustion gives $0.72 \mathrm{g}$ of water and $3.08 \mathrm{g}$ ${\mathrm{CO}}_2$. What is the empirical formula of the hydrocarbon?

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time, the passage of air is stopped, but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $\mathrm{kg}$) of $\mathrm{Pb}$ produced per $\mathrm{kg}$ of ${\mathrm{O}}_2$ consumed is ____. (Atomic weights in $\mathrm{g}\mathrm{ }{\mathrm{mol}}^{-1}: \mathrm{O}=16,\mathrm{ }\mathrm{S}=32,\mathrm{ }\mathrm{Pb}=207$)

Give the answer to the nearest integer value.