Preparation and Properties of Potassium Oxide

Q. Effective magnetic moment can be calculated by using the formula (n- Number of unpaired electrons)

1. $\sqrt{n(n+1)}$
2. $\sqrt{n(n-1)}$
3. $\sqrt{n(n+2)}$
4. $\sqrt{n(n-2)}$

Q.

In which one of the hydrated crystals, water molecules present in the interstitial spaces?

1. ${\mathrm{BaCl}}_2.2{\mathrm{H}}_2\mathrm{O}$

2. $\left[\mathrm{Cu}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\left({\mathrm{NH}}_3\right)}_2\right]{\mathrm{Cl}}_2$

3. ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$

4. $[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_5{]}^{3+}.3{\mathrm{Cl}}^{-}$

Q. What is the oxidation number of $Mn$ in $KMn{O}_4,K_{2}Mn{O}_4,MnS{O}_4,Mn{O}_2$ and ${Mn}_3{O}_4$ respectively?

1. $+4,+6,+2,+4,$ $+\frac{8}{3}$
2. $+7,+6,+2,+4,$ $+\frac{8}{3}$
3. $+7,+6,+2,+3,$ $+\frac{8}{3}$
4. None of these

Q. Oxidation number of potassium in $K_{2}O$, $K_2{O}_2$ and $K{O}_2$, respectively, is:

1. $+2$, $+1$ and $+\frac{1}{2}$
2. $+1$, $+4$ and $+2$
3. $+1$, $+1$ and $+1$
4. $+1$, $+2$ and $+4$

Q. Calculate the magnetic moment of $C{r}^{3+}$.

1. 2.9
2. 3.57
3. 4.12
4. 3.87

Q. Which of the following statements is/are true?

1. $K_{2}O$ has antifluorite structure
2. In $K_{2}O$ crystal, the potassium ions are coordinated to 4 oxide ions
3. In $K_{2}O$ crystal, the oxide ions are coordinated to 8 potassium ions
4. $K_{2}O$ is the simplest oxide of potassium and it is highly reactive

Q.

If the magnetic moment of a complex compound is 2.8 B.M. Then the number of unpaired electrons in compound is:

1. 1
2. 3
3. 2
4. 4

Q. The oxidation number of Phosphorus in $M{g}_2{P}_2{O}_7$ is:

1. + 3
2. + 2
3. + 5
4. - 3

Q. Which of the following statements is/are true?

1. K₂O has antifluorite structure

2. In K₂O crystal, the potassium ions are coordinated to 4 oxide ions

3. In K₂O crystal, the oxide ions are coordinated to 8 potassium ions

4. K₂O is the simplest oxide of potassium and it is highly reactive

Q. The sum of oxidation number of the metals in the following species is:

1. 20
2. 23
3. 18
4. 21

Q. $Mn$ in $K_{2}Mn{O}_4,K_{2}Mn{O}_3,M{n}_3{O}_4,MnS{O}_4$ and $K_{3}Mn{F}_6$.

1. $6,4,\frac{8}{3},2,3$
2. $10,5,\frac{8}{3},3,3$
3. $6,5,8,2,3$
4. None of the above

Q. In calcium hypophosphite, oxidation number of phosphorus is

1. $+3$
2. $0$
3. $+5$
4. $+1$

Q. Oxidation number of $Fe$ in $N{a}_2\left[Fe\right(CN{)}_5\left(NO\right)].2H_{2}O$ is____________.

1. $+3$
2. $+5$
3. $-2$
4. $+1$

Q. The oxidation number of phosphorus in $P{O}_4^{3-},P_4{O}_{10}$ and $P_2{O}_7^{4-}$ is:

1. 3
2. 2
3. -3
4. 5

Q. What is the oxidation number of chlorine in $Cl{O}_3^{-}$?

1. $+5$
2. $+3$
3. $+4$
4. $+2$

Q. Magnetic moment of $X^{n+}(Z=26)$is $\sqrt{24}$ B.M. Hence number of unpaired electrons and value of n respectively are :

1. $2,4$
2. $4,2$
3. $0,2$
4. $3,1$

Q. The oxidation state of chromium in $Cr{\left(CO\right)}_6$ is :

1. $+2$
2. $0$
3. $-2$
4. $+6$

Q. ${Fe}^{2+}$ is oxidised by $Mn{O}_4^{-}$ or ${Cr}_2{O}_7^{2-}$ in acidic medium. What is new oxidation number of Fe?

1. $+3$
2. $+1$
3. $+2$
4. $+4$

Q. The magnetic moment of $K{O}_2$ at room temperature is ____ BM.

1. 1.41
2. 1.73
3. 2.23
4. 2.64

Q. The oxidation number of $Cr$ in $Cr{O}_5$ is:

1. $+10$
2. $+8$
3. $+6$
4. $+4$

Q. The complex having the highest magnetic moment is :

1. $\left[Cr\right(H_{2}O{)}_6{]}^{2+}$
2. $\left[Zn\right(H_{2}O{)}_6{]}^{2+}$
3. $\left[Mn\right(H_{2}O{)}_6{]}^{2+}$
4. $\left[Cu\right(H_{2}O{)}_6{]}^{2+}$

Q. Valency of potassium ($K$) in $K_{4}Fe(CN{)}_6$ is :

1. 1
2. 2
3. 2/3
4. 4

Q. The oxidation number of $Cr$ in $K_{2}C{r}_2{O}_7$ is :

1. $+3$
2. $-3$
3. $+6$
4. $-6$

Q. The magnetic moment of $\left[Cu\right(N{H}_3{)}_4{]}^{2+}$ was found to be 1.73 B.M. The number of unpaired electrons in the complex is:

1. 0
2. 2
3. 3
4. 1

Q. The oxidation state of chromium in $\left[Cr{\left(PP{h}_3\right)}_3{\left(CO\right)}_3\right]$ is :

1. $+8$
2. $+3$
3. $0$
4. $+5$

Q. Assertion :Solution of $N{a}_{2}Cr{O}_4$ in water is intensely coloured. Reason: Oxidation state of $Cr$ in $N{a}_{2}Cr{O}_4$ is +VI.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. What are the oxidation numbers of each element in $Ca(OH{)}_2$?

Q. The magnetic moment of a complex is $4.9$ B.M. Thus, unpaired electron(s) maybe _______

Q. Chooe the correct amswer using given codes. Use T if statement is true and F if it is false.
(I) Sulphide ions reacts with $N{a}_2\left[Fe\right(CN{)}_5\left(NO\right)]$ to form a purple coloured compound $N{a}_4\left[Fe\right(CN{)}_5\left(NOS\right)]$. In the reaction, the oxidation state of iron changes.
(II) $Pt\left(IV\right)$ compounds are relatively more stable than $Ni\left(IV\right)$ compounds.
(III) The welding of magnesium can be done in the atmosphere of helium.
(IV) $LiAI{H}_4$ on hydrolysis will give $H_2$.

1. TFTF
2. TFTT
3. FFTT
4. FTTT

Q. Oxidation number of potassium in $K_{2}O$, $K_2{O}_2$ and $K{O}_2$, respectively, is:

1. $+1$, $+1$ and $+1$
2. $+1$, $+2$ and $+4$
3. $+2$, $+1$ and $+\frac{1}{2}$
4. $+1$, $+4$ and $+2$