Identify the compound formed from elements $X, Y, Z$ having oxidation states $+2, +5, -2$ respectively.

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 $24 \, g \, mol^{-1}$,$N_{A} = 6.02 \times 10^{23} \, mol^{-1}$)

Which of the following compounds does not have similarity in their structural aspect?

Natural gas is a mixture of methane and ethane. The heat produced by the complete combustion of $10 \, L$ of this mixture at $S.T.P.$ is $476.6 \, kJ$. Given $\Delta H_{comb} (CH_4) = -894 \, kJ \, mol^{-1}$ and $\Delta H_{comb} (C_2H_6) = -1500 \, kJ \, mol^{-1}$,calculate the percentage of methane and ethane in the mixture by volume.

Assume that a human body requires $2500 \, kcal$ of energy each day for metabolic activity and sucrose is the only source of energy,as per the equation $C_{12}H_{22}O_{11(s)} + 12 \, O_{2(g)} \longrightarrow 12 \, CO_{2(g)} + 11 \, H_2O_{(l)};$ $\Delta H = -5.6 \times 10^6 \, J$. (Fill in the blanks) $(a)$ The energy requirement of the human body per day is $.... \, kJ$. $(b)$ The mass of sucrose required to provide this energy is $........ \, g$ and the volume of $CO_2$ (at $STP$) produced is $......... \, litres.$

Calculate the molarity of each of the following solutions: $(a)$ $30 \, g$ of $Co(NO_3)_2 \cdot 6H_2O$ in $4.3 \, L$ of solution $(b)$ $30 \, mL$ of $0.5 \, M \, H_2SO_4$ diluted to $500 \, mL$.