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s-Block and p-Block Elements

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When 1 mole of Mg3N2 is dissolved in water, it releases

  1. one mole ammonia

  2. one mole nitric acid

  3. two moles of ammonia

  4. two moles of nitric acid

  5. none of these


Correct Option: C
Explanation:

Two moles of ammonia gas are released.

In hypophosphorous acid, number of hydrogen atom(s) attached to phosphorus atom after ionisation in water is

  1. 0

  2. 1

  3. 2

  4. 3

  5. None of these


Correct Option: B
Explanation:

True statement. Out of 3 , only one H atom is ionisable. Rest 2 are permanently attached to P atom.

Identify the correct statement.

  1. H3PO4 is a stronger acid than H2SO4.

  2. HF is a stronger acid than HCl in an aqueous medium.

  3. HClO4 is a weaker acid than HClO3.

  4. HNO3 is a stronger acid than HNO2.

  5. None of these


Correct Option: D
Explanation:

Polarity along O-H in HNOis more in comparision to that in HNO2.

Identify the amphoteric compound.

  1. SnO2

  2. SiO2

  3. CO2

  4. CaO

  5. None of these


Correct Option: A
Explanation:

SnO2 in base forms SnCl4 and in acid forms SnO32-.

Which of the following fertilisers is used to increase the acidity of soil?

  1. Potassium nitrate

  2. Urea

  3. Superphosphate of lime

  4. Ammonium sulphate

  5. None of these


Correct Option: D
Explanation:

Ammonium ion (NH4)+ is acidic in nature.

What is the reason for using alum for purifying the water?

  1. It forms complex with clay particles.

  2. It coagulates the mud particles.

  3. It exchanges Ca2+ and Mg2+ ions present in hard water.

  4. Its sulphate ion is a water purifier.

  5. None of these


Correct Option: B
Explanation:

Mud is colloidal charged solution which on treatment with Alum (Al3+) gets neutralised or coagulated.

After reaction with potassium iodide and copper sulphate, sodium thiosulphate solution is added. Find the incorrect statement about this reaction.

  1. Cu2I2 is formed.

  2. CuI2 is formed.

  3. Na2S2O3 is oxidised.

  4. Evolved I2 is reduced.

  5. None of these


Correct Option: B
Explanation:

When KI is added to the solution of cupper sulphate, an equivalent amount of I2 is liberated along with the formation white precipitate (of Cu2I2). This free iodine (I2), which remains in solution as [KI3] complex is then titrated with sodium thiosulphate solution using starch as indicator. At the end point of the titration, the blue colour of solution will disappear and a white precipitate of the Cu2I2 will remain in conical. The reactions that are taking place are:  

Glass is categorised as

  1. a microcrystalline solid

  2. supercooled liquid

  3. gel

  4. polymeric mixture

  5. none of these


Correct Option: B
Explanation:

Glass is a supercooled liquid, which forms a non-crystalline solid. The common lime-soda glass used for bottles and jars is a super cooled mixture of sodium and calcium silicates.

Which property differs Be and Al from each other?

  1. Exhibiting maximum covalency in compounds

  2. Forming polymeric hydrides

  3. Forming covalent hydrides

  4. Exhibiting amphoteric nature in their oxides

  5. None of these


Correct Option: A
Explanation:

Be, Z = 4 has maximum covalency of 4 while Al, Z = 13 has maximum covalency of 6.

 

In which of the following is hard water produced?

  1. Saturation of water with calcium carbonate

  2. Saturation of water with magnesium carbonate

  3. Saturation of water with calcium sulphate

  4. Addition of sodium sulphate to water

  5. None of these


Correct Option: C
Explanation:

Ca and Mg soluble sulphates and chlorides cause permanent hardness. 

When small amount of sodium oxide is dissolved in water, then

  1. oxidation number of sodium decreases

  2. oxide ion accepts sharing in a pair of electrons

  3. oxide ion donates a pair of electrons

  4. oxidation number of oxygen increases

  5. none of these


Correct Option: C
Explanation:

Oxide ion donates a pair of electrons, thus changes to hydroxide ion. 

Lithium nitrate on heating forms

  1. lithium nitrite and oxygen gas

  2. lithium oxide, nitrogen dioxide and oxygen gas

  3. lithium nitride and oxygen gas

  4. lithium oxide, hydroxide and oxygen gas

  5. none of these


Correct Option: B
Explanation:

Correct statement. It forms lithium oxide, nitrogen dioxide and oxygen gas.

Which of the following anions of boron is not possible?

  1. BF63-

  2. BH4-

  3. B(OH)4-

  4. BO2-

  5. None of these


Correct Option: A
Explanation:

Due to absence of 2d-orbitals, the maximum covalency is four.

Which of the following information about sulphur is incorrect?

  1. Sulphur molecule is not diamagnetic.

  2. The vapour at 200oC consists mostly of S8 rings.

  3. At 600oC, the gas mainly consists of S2 molecules.

  4. The oxidation state of sulphur is never less than +4 in its compounds.

  5. None of these


Correct Option: D
Explanation:

Oxidation states of sulphur are - 2, 0, + 2, + 4, + 6. Valency can be less than 4. Incorrect statement

Identify the wrong statement.

  1. In group-15 of the periodic table, stability of hydrides increases from nitrogen hydride to bismuth hydride.

  2. d $\pi$ - p$\pi$ bond is not formed by nitrogen.

  3. Single P-P bond is stronger than single N-N bond.

  4. Two resonance structure is formed by N2O4.

  5. None of these


Correct Option: A
Explanation:

Thermal stability of hydrides decreases as we go down the group. Hence, this option is correct.

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