Potassium Dichromate

Q.

Find $\mathrm{n}$ factor of ${\mathrm{Na}}_2{\mathrm{CO}}_3$.

Q.

ph of a saturated solution of $Ca{\left(OH\right)}_2$ is 9. The solubility product($K_{sp}$ ) of ${Ca\left(OH\right)}_2$ is

Q.

The blue-green colour of the solution is due to the formation of copper(II) chloride in the reaction this is an example of which kind of chemical reaction?

Q. Hydrogenation of benzyl chloride in the presence of $Pd-BaS{O}_4$ is called -

1. Rosenmund reaction
2. Aldol condensation
3. Koch reaction
4. Gattermann reaction

Q. When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with $KCl$, orange crystals of compound (D) crystallise out. Identify A to D and also explain the reactions.

Q. Which of the following chloride does not respond to the chromyl chloride test?

1. NaCl
2. $MgC{l}_2$
3. $AlC{l}_3$
4. $H{g}_{2}C{l}_2$

Q.

On treating a compound with warm dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$ gas X is evolved which turns ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ paper acidified with dilute ${\mathrm{H}}_2{\mathrm{SO}}_4$ to a green compound Y. X and Y respectively are

1. $\mathrm{X}={\mathrm{SO}}_2,\mathrm{Y}={\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3$

2. $\mathrm{X}={\mathrm{SO}}_2,\mathrm{Y}={\mathrm{Cr}}_2{\mathrm{O}}_3$

3. $\mathrm{X}={\mathrm{SO}}_3,\mathrm{Y}={\mathrm{Cr}}_2{\mathrm{O}}_3$

4. $\mathrm{X}={\mathrm{SO}}_3,\mathrm{Y}={\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3$

Q.

Give evidence that [Co(NH₃)₅Cl]SO₄ and [Co(NH₃)₅SO₄]Cl are ionization isomers.

Q. Given below are the statements about diborane.
(a) Diborane is prepared by the oxidation of $NaB{H}_4$ with $I_2$.
(b) Each boron atom is in $s{p}^2$ hybridized state.
(c) Diborane has one bridged 3 centre-2-electron bond.
(d) Diborane is a planar molecule.

The option with correct statement(s) is :

1. (c) only
2. (a) and (b) only
3. (c) and (d) only
4. (a) only

Q. Which of the following is a cationic detergent?

1. Cetyltrimethyl ammonium bromide
2. Sodium dodecylbenzene sulphonate
3. Sodium lauryl sulphate
4. Sodium stearate

Q. Which of the statements is not true?

1. $K_{2}C{r}_2{O}_7$ solution in acidic medium is orange
2. $N{a}_{2}C{r}_2{O}_7$ is preferred over $K_{2}C{r}_2{O}_7$ in volumetric analysis
3. $K_{2}C{r}_2{O}_7$ solution becomes yellow on increasing the pH beyond 7
4. On passing $H_{2}S$ through acidified $K_{2}C{r}_2{O}_7$ solution, a milky colour is observed

Q.

In which of the following, heat energy will be evolved?

1. 1) Electrolysis of water

2. (2) Dissolution of ${\mathrm{NH}}_4\mathrm{Cl}$in water

3. (3) Burning of L.P.G.

4. (4) Decomposition of$\mathrm{AgBr}$ in the presence of sunlight

Q. Which one is formed when sodium phenoxide is heated with ethyl iodide?

1. Phenetole
2. Ethyl phenyl alcohol
3. Phenol
4. None of the above

Q.

How to memorize the colour of all the salts????

Q.

Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with

(i) Iodide

(ii) Iron

(iii) $H_{2}S$

Q. The yellow colored solution of chromate salt changes to orange colour on acidification due to the formation of

1. $C{r}^{3+}$
2. $C{r}_2{O}_7^{2-}$
3. $Ti{O}_4^{-}$
4. $C{r}_2{O}_3$

Q.

Match the compounds given in Column I with the oxidation state of cobalt present in it (given in column II) and assign the correct code.

$\begin{array}{cc}\text{Column~I}& \text{Column~II}\\ \left(Compound\right)& \left(OxidationstateofCo\right)\\ A.\left[Co\right(NCS\left)\right(N{H}_3{)}_5\left]\right(S{O}_3)& 1.+4\\ B.\left[Co\right(N{H}_3{)}_{4}C{l}_2]S{O}_4& 2.0\\ C.N{a}_4\left[Co\right(S_2{O}_3{)}_3]& 3.+2\\ A.\left[C{o}_2\right(CO{)}_8]& 4.+3\end{array}$

Code

$\begin{array}{ccccc}& A& B& C& D\\ \left(a\right)& 1& 2& 4& 3\\ \left(b\right)& 4& 3& 2& 1\\ \left(c\right)& 3& 1& 4& 2\\ \left(d\right)& 4& 1& 3& 2\end{array}$

Q.

Describe the preparation of potaislum dichromate from iron ohromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

Q.

Complete and balance the following equation.

$\mathrm{Al}+\mathrm{KOH}\to$

Q.

H_{​​​​​​2}S is acidic while H_{​​​​​​2}​​​O is neutral.Why?

Q.

How can you find $\mathrm{pH}$ of the solution?

Q. Equivalent conductance of 0.1 M HA (weakacid) solution is 10 Scm2 equivalent1 and thatat infinite dilution is 200 Scm2 equivalent-1Hence pH of HA solution is. (approx)(1) 1.3(2) 1.7c(3)23 (4) 3.6

Q.

Give reasons for the following:

Chlorine water on standing loses its yellow colour

Q. $C{r}_2{O}_7^{2-}\stackrel{pH=x}{\to }Cr{O}_4^{2-}\stackrel{pH=y}{\to }C{r}_2{O}_7^{2-}$.The `pH` values of x and y can be:

1. 4 and 8
2. 8 and 4
3. 4 and 5
4. 8 and 9

Q. Consider the coordination compound, Na₂[Pt(CN)₄]. The Lewis acid is

1. [Pt(CN)₄]^2-
2. Na⁺
3. Pt²⁺
4. Pt
5. CN^-

Q.

Which of the following has $\mathrm{S}-\mathrm{S}$bond?

1. ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_5$

2. ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_6$

3. ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7$

4. ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_8$

Q. In which of the following reactions $H_2{O}_2$ acts as a reducing agent?

$\begin{array}{c}I.H_2{O}_2+2H^{+}+2e^{-}\\ \downarrow \\ 2H_{2}O\end{array}$
II. $H_2{O}_2-2e^{-}\to O_2+2H^{+}$
III. $H_2{O}_2+2e^{-}\to 2O{H}^{-}$
$\begin{array}{c}IV.H_2{O}_2+2H^{+}+2e^{-}\\ \downarrow \\ O_2+2H_{2}O\end{array}$

1. I and II
2. II and IV
3. III and IV
4. I and III

Q. In both crystalline NaHCO3 and KHCO3, HCO3- forms only dimeric anion through hydrogen bond.justify this statement.

Q. 21. Ammonium hydrogen sulphide dissociate as follows NH4HS(s) <=>NH3(g)+H2S(g), if solid NH4HS is placed in an evacuated flask at certain temperature it will dissociate until the total pressure is 600 torr. (a) calculate the value of equilibrium constant for the dissociation reaction. (b) additional NH3 is introduced into the equilibrium mixture without changing the temperature until partial pressure of NH3 is 750 torr, what is the partial pressure of H2S under these conditions? What is the total pressure in the flask?

Q. Which of the following is not formed when $H_{2}S$ reacts with acidic $K_{2}C{r}_2{O}_7$ solutions?

1. $K_{2}S{O}_4$
2. $C{r}_2(S{O}_4{)}_3$
3. $S$
4. $CrS{O}_4$