KCET · Chemistry · Solutions
A sample of water is found to contain \(5.85 \%\) \(\left(\frac{w}{w}\right)\) of \(A B\) (molecular mass 58.5 ) and \(9.50 \%\) \(\left(\frac{w}{w}\right) X Y_2\) (molecular mass 95). Assuming \(80 \%\) ionisation of \(A B\) and \(60 \%\) ionisation of \(X_2\), the freezing point of water sample is [Given, \(K_f\) for water \(1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\),
Freezing point of pure water is \(273 \mathrm{~K}\) and \(A\), \(B\) and \(Y\) are monovalent ions.]
- A \(264.25 \mathrm{~K}\)
- B \(265.56 \mathrm{~K}\)
- C \(280.44 \mathrm{~K}\)
- D \(281.75 \mathrm{~K}\)
Answer & Solution
Correct Answer
(A) \(264.25 \mathrm{~K}\)
Step-by-step Solution
Detailed explanation
\(A B \quad X Y_2\)
\(5.85 \%\)
\(9.5 \%\)
\(\begin{array}{rlrl}m & =\frac{5.85}{58.5} \times \frac{1000}{84.65} \quad m & =\frac{9.5}{95} \times \frac{1000}{84.65} \\ & =1.181 & & =1.181\end{array}\)
\(\alpha=0.8\) (for \(80 \%\) ionisation) \(\alpha=0.6\)
(for \(60 \%\) ionisation)
\(\begin{array}{rlrl}i & =1+(2-1) 0.8 & i & =1+(3-1) 0.6 \\ & =1.8 & & =2.2\end{array}\)
Now, \(\Delta T_f=K_f\left[i_1 m_1+i_2 m_2\right]\)
\(\begin{aligned} & =1.86[1.8(1.181)+2.2(1.181)] \\ & =1.86[4.72]=8.78\end{aligned}\)
\(5.85 \%\)
\(9.5 \%\)
\(\begin{array}{rlrl}m & =\frac{5.85}{58.5} \times \frac{1000}{84.65} \quad m & =\frac{9.5}{95} \times \frac{1000}{84.65} \\ & =1.181 & & =1.181\end{array}\)
\(\alpha=0.8\) (for \(80 \%\) ionisation) \(\alpha=0.6\)
(for \(60 \%\) ionisation)
\(\begin{array}{rlrl}i & =1+(2-1) 0.8 & i & =1+(3-1) 0.6 \\ & =1.8 & & =2.2\end{array}\)
Now, \(\Delta T_f=K_f\left[i_1 m_1+i_2 m_2\right]\)
\(\begin{aligned} & =1.86[1.8(1.181)+2.2(1.181)] \\ & =1.86[4.72]=8.78\end{aligned}\)
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Chemistry
- Methane can be converted into ethane by the reactionsKCET 2013 Easy
- The reaction of Benzenediazonium chloride with aniline yields yellow dye. The name of the
yellow dye isKCET 2018 Easy - \( \left(\mathrm{CH}_{3}\right)_{3} \mathrm{SiCl} \) is used during polymerization of organosilicons becauseKCET 2018 Easy
- The volume of \(10 \mathrm{~N}\) and \(4 \mathrm{~N} \mathrm{HCl}\) required to make \(1 \mathrm{~L}\) of \(7 \mathrm{~N} \mathrm{HCl}\) areKCET 2007 Easy
- For a cell reaction involving two electron changes, \( E_{\text {cell }}^{\circ}=0.3 \mathrm{~V} \) at \( 25^{\circ} \mathrm{C} \). The cell equilibrium
constant of the reaction isKCET 2018 Medium - For \(n\)th order of reaction, half-life period is directly proportional toKCET 2022 Easy
More PYQs from KCET
- The maximum value of \(z=3 x+4 y\), subject to the constraints \(x+y \leq 40, x+2 y \leq 60\) and \(x, y \geq 0\) isKCET 2025 Medium
- Which of the following colligative properties can provide molar mass of proteins, polymers and colloids with greater precision?KCET 2022 Easy
- A uniform electric field \(E=3 \times 10^5 \mathrm{NC}^{-1}\) is acting along the positive \(Y\)-axis. The electric flux through a rectangle of area \(10 \mathrm{~cm} \times 30 \mathrm{~cm}\) whose plane is parallel to the ZX -plane isKCET 2024 Easy
- \(5 \mathrm{~mL}\) of \(0.4 \mathrm{~N} \mathrm{NaOH}\) is mixed with \(20 \mathrm{~mL}\) of \(0.1 \mathrm{~N} \mathrm{HCl}\). The \(\mathrm{pH}\) of the resulting solution will beKCET 2012 Hard
- At \(500 \mathrm{~K}\), for a reversible reaction \(A_2(g)+B_2(g) \rightleftharpoons 2 A B(g)\) in a closed container, \(K_C=2 \times 10^{-5}\). In the presence of catalyst, the equilibrium is attaining 10 times faster. The equilibrium constant \(K_C\) in the presence of catalyst at the same temperature isKCET 2023 Easy
- Pick out the WRONG statements about magnetic substances.
(\(\chi\) = magnetic susceptibility)
(\(\mu_r\) = relative permeability).
I. Substances with \(-1 \leq \chi < 0\) are diamagnetic.
II. Substances with \(\chi \gg 1\) are paramagnetic.
III. Substances with \(\chi \ll 1\) are ferromagnetic.
IV. Substances with \(\mu_r \gg 1\) are ferromagnetic.KCET 2026 Medium