Phenolphthalein is used as an indicator for the titration of sodium hydroxide solution against a standard solution of oxalic acid. The colour change that is observed at an alkaline pH close to the equivalence point during this titration is:
pinkish red to yellow
yellow to pinkish red
pink to colourless
colourless to pink
When $1 \mathrm{dm}^3$ of CO2 gas is passed over hot coke the volume of gaseous mixture after complete reaction at STP becomes $1.4 \mathrm{dm}^3$. The composition of the gaseous mixture at STP is :
$0.8 \mathrm{dm}^3$ of $\mathrm{CO}, 0.8 \mathrm{dm}^3$ of $\mathrm{CO}_2$
$0.8 \mathrm{dm}^3$ of $\mathrm{CO}, 0.6 \mathrm{dm}^3$ of $\mathrm{CO}_2$
$0.6 \mathrm{dm}^3$ of $\mathrm{CO}, 0.8 \mathrm{dm}^3$ of $\mathrm{CO}_2$
$0.6 \mathrm{dm}^3$ of $\mathrm{CO}, 0.4 \mathrm{dm}^3$ of $\mathrm{CO}_2$
The major product Z formed in the following sequence of reactions is
$\mathrm{C}_2 \mathrm{H}_5 \mathrm{NO}_2$
$\mathrm{C}_2 \mathrm{H}_5-\mathrm{N}=\mathrm{N}-\mathrm{OH}$
$\mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}$
$\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$
Given below is an expression for the rate constant of a first-order reaction occurring at a certain temperature, $\mathrm{T}(\mathrm{K})$.
$$ \operatorname{lnk}=14.34-\frac{1.25 \times 10^4}{T} $$
The energy of activation in $\mathrm{kcal} \mathrm{mol}^{-1}$ for the reaction is :
(Given: $\mathrm{k}^{-1} \mathrm{~s} \mathrm{~s}^{-1}, \mathrm{R}=1.987 \mathrm{cal} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$ )
24.84
14.34
18.63
12.42
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