The active ingredients of an antacid tablet contained only magnesium hydroxide and aluminium hydroxide. Complete neutralisation of the sample of the active ingredients required $48.5 \mathrm{mL}$ of $0.187 \mathrm{M}$ hydrochloric acid. The chloride salts from the neutralisation were obtained by the evaporation of the filtrate from the titration; they weighed $0.42 \mathrm{g}$. What was the percentage by mass of magnesium hydroxide in the active ingredients of the antacid tablet? $\left(\mathrm{Mg}=24, \mathrm{Al}=27, \mathrm{Cl}=35.5, \mathrm{O}=16. \mathrm{H}=1\right)$

Round off your answer up to one place of decimal.

In a reaction

${\mathrm{CH}}_3{\mathrm{COOCH}}_3 \left(\mathrm{aq}\right) + {\mathrm{OH}}^{-} \left(\mathrm{aq}\right)\to {\mathrm{CH}}_3{\mathrm{COO}}^{-} \left(\mathrm{aq}\right) + {\mathrm{CH}}_3\mathrm{OH} \left(\mathrm{aq}\right)$,

the overall order of the reaction was determined by starting with methyl acetate and hydroxide ion at the same concentrations, so, $\left[{\mathrm{CH}}_3{\mathrm{COOCH}}_3\right]=\left[{\mathrm{OH}}^{-}\right]=x$

Then, the rate $=\mathrm{k}{\left[{\mathrm{CH}}_3{\mathrm{COOCH}}_3\right]}^{\mathrm{m}} [{\mathrm{OH}}^{-}{]}^{\mathrm{n}}={\mathrm{kx}}^{\mathrm{m}+\mathrm{n}}$

Determine the overall order and the value of the rate constant, $\mathrm{k}$, from the following data:

$\begin{array}{cc}\text{ Time (min) }& \left[{\mathrm{CH}}_3{\mathrm{COOCH}}_3\right]\text{ (mole/litre) }\\ 0.00& 0.01\\ 3.00& 0.0074\\ 4.00& 0.00683\\ 5.00& 0.00634\end{array}$

A sample of natural gas is $85.2\%$ of methane (${\mathrm{CH}}_4$) and $14.8\%$ of ethane (${\mathrm{C}}_2{\mathrm{H}}_6$) by mass. What would be the density $\left(\mathrm{in} \mathrm{g}/\mathrm{L}\right)$ of this mixture at $18°\mathrm{C}$ and $748 \mathrm{mmHg}$?

Answer by rounding off up to two places of decimals.

If the RMS speed of the ${\mathrm{NH}}_3$ molecule is found to be $0.51 \mathrm{km}/\mathrm{s}$, what is the temperature (in Kelvin)? $\left(\mathrm{R}=8.314 \mathrm{J} {\mathrm{mol}}^{-1} {\mathrm{K}}^{-1}\right)$

Round off your answer up to two places of decimals.

Calculate the effective neutron capture radius of a nucleus having a cross-section of $1.0$ barn. If the answer is of type $\mathrm{y}\times {10}^{-13} \mathrm{cm}$, report the value of $\mathrm{y}$ correct up to two places of decimals.

New industrial plants for acetic acid react liquid methanol with carbon monoxide in the presence of a catalyst.

${\mathrm{CH}}_3\mathrm{OH} + \mathrm{CO}\to {\mathrm{CH}}_3\mathrm{COOH}$

In the experiment, $15 \mathrm{g}$ of methanol and $10 \mathrm{g}$ of carbon monoxide were placed in a reaction vessel. What is the theoretical yield of acetic acid? If the actual yield is $19.1 \mathrm{g},$ what is the percentage yield?

A $1.0 \mathrm{mg}$ sample of technetium has an activity of $1.7\times {10}^{-5} \mathrm{Ci}$ decaying by $\beta$-emission. What is the decay constant for ${}_{43}{}^{99}\mathrm{Tc}$ ?

If the answer is of type $\mathrm{y}\times {10}^{-13} {\mathrm{s}}^{-1}$, report the value of $\mathrm{y}$ correct up to one place of decimal.

Crystals of $\mathrm{AgBr}$ can be removed from the black-and-white photographic film by reacting the $\mathrm{AgBr}$ with sodium thiosulphate.

$\mathrm{AgBr}\left(\mathrm{s}\right) + 2{\mathrm{S}}_2{\mathrm{O}}_3^{2-}\left(\mathrm{aq}\right) \rightleftharpoons {\left[\mathrm{Ag}{\left({\mathrm{S}}_2{\mathrm{O}}_3\right)}_2\right]}^{3-}\left(\mathrm{aq}\right) + {\mathrm{Br}}^{-}\left(\mathrm{aq}\right)$