In which of the following reactions is no gas evolved on the product side? (Temperature is maintained below the boiling point of liquids formed)

Iron sulphide is heated in air to form $A$,an oxide of sulphur. $A$ is dissolved in water to give an acid. The basicity of this acid is:

An athlete is given $100 \ g$ of glucose $(C_6H_{12}O_6)$ for energy. This is equivalent to $1800 \ kJ$ of energy. The $50 \ \%$ of this energy gained is utilized by the athlete for sports activities at the event. In order to avoid storage of energy,the weight of extra water he would need to perspire is $......... \ g$ (Nearest integer).
Assume that there is no other way of consuming stored energy. Given: The enthalpy of evaporation of water is $45 \ kJ \ mol^{-1}$.
Molar mass of $C, H$ and $O$ are $12, 1$ and $16 \ g \ mol^{-1}$.

$A$ 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: $hc = 12400 \ eV \mathring{A}$,$1 \ eV/atom = 96 \ kJ/mol$]

What is the importance of chemistry?

$A$ metal oxide contains $75 \%$ metal by mass. If the vapour density of the metal chloride is $89$,what is the atomic weight of the metal?