When $400 \ mL$ of $0.2 \ M \ H_2SO_4$ is mixed with $600 \ mL$ of $0.1 \ M \ NaOH$, the heat evolved is $3.43 \ kJ$. If the specific heat of water is $4.18 \ J \ K^{-1} \ g^{-1}$, the rise in temperature of the final solution will be ........... $K$. (Assume the specific heat capacity of the final solution is the same as that of water)

$3.0$ molal $NaOH$ solution has a density of $1.110 \, g/mL$. The molarity of the solution is

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 $500 \, mL$.

What volume of $NH_3$ gas at $STP$ would be needed to prepare $100 \ mL$ of $2.5$ molal $(2.5 \ m)$ ammonium hydroxide solution? (Assume the density of the solution is $1 \ g/mL$)

$A + 2B \rightarrow AB_{2}$. $36.0 \ g$ of '$A$' (Molar mass: $60 \ g \ mol^{-1}$) and $56.0 \ g$ of '$B$' (Molar mass: $80 \ g \ mol^{-1}$) are allowed to react. Which of the following statements are correct?
$(A)$ '$A$' is the limiting reagent
$(B)$ $77.0 \ g$ of $AB_{2}$ is formed
$(C)$ Molar mass of $AB_{2}$ is $220 \ g \ mol^{-1}$
$(D)$ $15.0 \ g$ of '$A$' is left unreacted after the completion of reaction.
Choose the correct answer from the options given below:

Which of the following has the minimum number of oxygen atoms?