Partially dried soil contains $50 \%$ silica and $7 \%$ water. If the original soil contained $12 \%$ water,then the percentage of silica in the original soil is .............. $\%$.

Chlorophyll extracted from the crushed green leaves was dissolved in water to make $2 \, L$ solution of $Mg$ of concentration $48 \, ppm$. The number of atoms of $Mg$ in this solution is $x \times 10^{20}$ atoms. The value of $x$ is (Nearest Integer) (Given : Atomic mass of $Mg$ is $24 \, g \, mol^{-1}$,$N_{A} = 6.02 \times 10^{23} \, mol^{-1}$)

$(i)$ Calculate the total number of electrons present in one mole of methane.
$(ii)$ Find $(a)$ the total number and $(b)$ the total mass of neutrons in $7 \, mg$ of $^{14}C$. (Assume that mass of a neutron $= 1.675 \times 10^{-27} \, kg$).
$(iii)$ Find $(a)$ the total number and $(b)$ the total mass of protons in $34 \, mg$ of $NH_3$. Will the answer change if the temperature and pressure are changed?

$10 \, mL$ of concentrated $H_2SO_4$ $(18 \, M)$ is diluted to $1 \, L$. The approximate strength of the dilute acid is.....$N$

$A$ photon having a wavelength of $310 \ nm$ is used to break the bond of an $A_2$ molecule with a bond energy of $288 \ kJ \ mol^{-1}$. Calculate the percentage of the photon's energy that is converted into kinetic energy $(K.E.)$. [Given: $hc = 12400 \ eV \mathring{A}$,$1 \ eV/atom = 96 \ kJ/mol$]

Which of the following has the maximum mass?