The mass of $CO_2$ that shall be obtained by heating $10 \ kg$ of $80\%$ pure limestone $(CaCO_3)$ is $:-$ (in $kg$)

Two elements $A$ and $B$ form $0.15 \ mol$ of $A_2 B$ and $AB_3$ type compounds. If $0.15 \ mol$ of both $A_2 B$ and $AB_3$ weigh equally,then the atomic weight of $A$ is $...$ times the atomic weight of $B$.

In an experiment on the enthalpy of neutralisation of sodium hydroxide with sulphuric acid,$50 \ cm^3$ of $0.4 \ M$ sodium hydroxide were titrated thermometrically with $0.25 \ M$ sulphuric acid. Which of the following plots gives the most probable correct representation of the temperature of the solution (initial temperatures of $NaOH$ and $H_2SO_4$ are the same)?

If $500 \ mL$ of $CaCl_2$ solution contains $3.01 \times 10^{22}$ chloride ions,the molarity of the solution will be: (in $M$)

$9.3 \ g$ of aniline is subjected to reaction with excess of acetic anhydride to prepare acetanilide. The mass of acetanilide produced if the reaction is $100 \%$ completed is $x \times 10^{-1} \ g$. Find the value of $x$. (Given molar mass in $g \ mol^{-1}: N: 14, O: 16, C: 12, H: 1$)

When $10 \ g$ of $90 \%$ pure limestone is heated,the approximate volume $($in $L$ $)$ of $CO_2$ liberated at $\text{STP}$ is: