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An important facility for 12th class students preparing for short questions chemistry 12th class chapter 4 of BISE. Get hundreds of questions to prepare and get better marks in 12th chemistry
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Question: 1
Write the formulas of (a) Phosphorite (b) Chile saltpeter.
Answer: 1
1-19
a) Phosphorite: Ca3(PO4)2
b) Chile saltpeter: NaNO3
Question: 2
How does nitrogen differ from other elements of its group?Give four points.
Answer: 2
2-19
i)Nitrogen is diatomic gas and occurs in free state while other members tetra atomic solids and occur in combines state.
Question: 3
Describe Ring test for confirmation of presence of nitrate ions in solution?
Answer: 3
3-19
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
FeSO4(aq)+ NO(g)--------->FeSO4.NO(aq)
Question: 4
How does HNO3act as an oxidizing agent?
Answer: 4
4-19
It acts as a strong oxidizing agent due to the ease with which it is decomposed.
2HNO3(aq)---------->H2O + 2NO2(g) +[O](g)
Question: 5
Name three allotropic forms of phosphorous>
Answer: 5
5-19
Phosphorus can exist in at least six different solid allotropic forms.But here mentioned only three.
Question: 6
How HNO3can be two metals which evolve hydrogen upon reaction with HNO3?
Answer: 6
6-19
In laboratory,nitric acid is prepared by heating potassium nitrate crystals with concentrated sulphuric acid.
KNO3(s)+ H2SO4(conc)---------->KHSO4(aq)+ HNO3(aq)
Question: 7
How does HNO3act as an oxidizing agent?
Answer: 7
7-19
It acts as a strong oxidizing agent due to the ease with which it is decomposed.
2HNO3(aq)---------->H2O + 2NO2(g) +[O](g)
Question: 8
Why Dinitrogen Oxide is called Laughing gas?
Answer: 8
8-19
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: 9
Write names and formulas of oxyacids of nitrogen.
Answer: 9
9-19
Name Formula
1.
Nitrous Acid HNO2
2. Nitric Acid
HNO3
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
Write any four uses of nitric acid?
Answer: 11
11-19
i) It is used as laboratory reagent.
Question: 12
What is aqua-regia?
Answer: 12
12-19
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.
HNO3(conc)+ 3HCI(conc)---------NOCI(aq)+ Cl2(g) + 2H2O(l)
Question: 13
Give definition of allotropy. Write allotropes of phosphorus.
Answer: 13
13-19
Definition:When an elements exist in different crystalline forms.These crystalline forms are called allotropic forms and this phenomenon is called allotropy.
Question: 14
How H3PO4is prepared on large scale?
Answer: 14
14-19
It is prepared by dissolving phosphorus trioxide in cold water.
P2O3+ 3H2O------->H3PO3
Question: 15
Write two dissimilarities of oxygen and sulphur?
Answer: 15
15-19
Oxygen:1) It is gas at ordinary temperature.
2) Oxygen is sparingly soluble in water.
3) It is paramagnetic in nature.
Question: 16
Justify that H2SO4is a king of chemicals?
Answer: 16
16-19
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: 17
Why SO3is dissolved in H2SO4and not in water?
Answer: 17
17-19
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: 18
Give the advantage of contact process for the manufacture of sulphuric acid.
Answer: 18
18-19
i) Contact process gives good yield of sulphuric acid.
ii) Contact process produce sulphuric acid which is in its pure form.
Question: 19
Give name and formulas of Oxyacids of Phosphorous.
Answer: 19
19-19
Name Formula
Phosphoric acid H3PO3
Orthophosphoric acid H3PO4
Pyrophosphoric acid H4P2O7
Metaphosphoric acid HPO3