12th Class Chemistry Chapter 4 Short Questions with Answers Solved

Question: 1

Describe Ring test for confirmation of presence of nitrate ions in solution?

Answer: 1

1-19

To the aqueous solution of NO₃ions add FeSO₄solution.Shake it well and add concentrated H₂SO₄along the side of test tube.It forms a ring of brown coloured addition compound at the junction of two liquids due to the addition compound formed by the action of NO produced wit FeSO₄
FeSO_4(aq)+ NO_(g)--------->FeSO₄.NO_(aq)

Question: 2

How does HNO₃act as an oxidizing agent?

Answer: 2

2-19

It acts as a strong oxidizing agent due to the ease with which it is decomposed.
2HNO_3(aq)---------->H₂O + 2NO₂(g) +[O]_(g)

Question: 3

Name three allotropic forms of phosphorous>

Answer: 3

3-19

Phosphorus can exist in at least six different solid allotropic forms.But here mentioned only three.

Question: 4

Give definition of allotropy. Write allotropes of phosphorus.

Answer: 4

4-19

Definition:When an elements exist in different crystalline forms.These crystalline forms are called allotropic forms and this phenomenon is called allotropy.

Question: 5

Write names and formulas of oxyacids of nitrogen.

Answer: 5

5-19

Name Formula
1.Nitrous Acid HNO_{2
2. Nitric Acid}HNO₃

Question: 6

Write any four uses of nitric acid?

Answer: 6

6-19

i) It is used as laboratory reagent.

Question: 7

How HNO₃can be two metals which evolve hydrogen upon reaction with HNO₃?

Answer: 7

7-19

In laboratory,nitric acid is prepared by heating potassium nitrate crystals with concentrated sulphuric acid.
KNO_3(s)+ H₂SO_4(conc)---------->KHSO_4(aq)+ HNO_3(aq)

Question: 8

What is aqua-regia?

Answer: 8

8-19

When one volume of concentrated HNO₃is mixed with three volume of concentrated HCI,aqua regia is formed.It is employed to dissolve gold and platinum.

HNO_3(conc)+ 3HCI_(conc)---------NOCI_(aq)+ Cl_2(g)+ 2H₂O_(l)

Question: 9

How does HNO₃act as an oxidizing agent?

Answer: 9

9-19

It acts as a strong oxidizing agent due to the ease with which it is decomposed.
2HNO_3(aq)---------->H₂O + 2NO₂(g) +[O]_(g)

Question: 10

Write any four important uses of H₂SO₄?

Answer: 10

10-19

i) It is used in manufacturing of fertilizers like ammonium sulphate and calcium superphosphate.

Question: 11

Why Dinitrogen Oxide is called Laughing gas?

Answer: 11

11-19

Its mixture with a little oxygen,if inhaled for a sufficiently long time,produces hysterical laughter,hence it is also known as laughing gas.

Question: 12

Write the formulas of (a) Phosphorite (b) Chile saltpeter.

Answer: 12

12-19

a) Phosphorite: Ca₃(PO₄)2
b) Chile saltpeter: NaNO₃

Question: 13

How does nitrogen differ from other elements of its group?Give four points.

Answer: 13

13-19

i)Nitrogen is diatomic gas and occurs in free state while other members tetra atomic solids and occur in combines state.

Question: 14

Write two dissimilarities of oxygen and sulphur?

Answer: 14

14-19

Oxygen:1) It is gas at ordinary temperature.
2) Oxygen is sparingly soluble in water.
3) It is paramagnetic in nature.

Question: 15

Justify that H₂SO₄is a king of chemicals?

Answer: 15

15-19

H₂SO₄has many applications in daily life,laboratories,industries etc.What's common to petrol,fertilizers,cars and soap?They,like a lot of other things require sulfuric acid to be made.That's why sulfuric acid is called the king of chemicals.

Question: 16

Why SO₃is dissolved in H₂SO₄and not in water?

Answer: 16

16-19

SO₃is not directly dissolved in water,since absorption is incomplete and mist of SO₃and H₂SO₄fills the factory,which causes great causes great inconvenience the workers.Therefor,SO₃is absorbed in concentrated H₂SO₄and Oleum(H₂S₂O₇) formed can be converted to sulphuric acid of any strength by mixing adequate quantities of water.

Question: 17

Give the advantage of contact process for the manufacture of sulphuric acid.

Answer: 17

17-19

i) Contact process gives good yield of sulphuric acid.
ii) Contact process produce sulphuric acid which is in its pure form.

Question: 18

Give name and formulas of Oxyacids of Phosphorous.

Answer: 18

18-19

Name Formula
Phosphoric acid H₃PO₃
Orthophosphoric acid H₃PO₄
Pyrophosphoric acid H₄P₂O₇
Metaphosphoric acid HPO₃

Question: 19

How H₃PO₄is prepared on large scale?

Answer: 19

19-19

It is prepared by dissolving phosphorus trioxide in cold water.
P₂O₃+ 3H₂O------->H₃PO₃

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12th Class Chapter 4 Chemistry Short Questions

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