Ask questions, doubts, problems and we will help you..
Ask questions which are clear, concise and easy to understand.
Ask Question
CBSE, JEE, NEET, CUET
Question Bank, Mock Tests, Exam Papers
NCERT Solutions, Sample Papers, Notes, Videos
Posted by Akash Mahto 5ย years, 3ย months ago (9214293)
- 1 answers
Posted by Seema Tanwer 5ย years, 3ย months ago (9796027)
- 0 answers
Posted by Yogesh Sahu 5ย years, 3ย months ago (9720471)
- 1 answers
Posted by R. Udhaya Kumar Udhaya 5ย years, 3ย months ago (9676157)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
Policy to hide: The strategy for states 'to hide' implies that the states should remain away from the dominant power. Practically, however, it is not possible for mega-states to follow this policy for any substantial length of time.
Posted by Md Junaid 5ย years, 3ย months ago (9876460)
- 2 answers
Silent King 5ย years, 3ย months ago (9281260)
Yogita Ingle 5ย years, 3ย months ago (2577571)
-
Simple permanent tissues
- epidermis
- parenchyma
- collenchyma
- sclerenchyma
Posted by Garima Patwa 5ย years, 3ย months ago (9876423)
- 1 answers
Posted by Gopal Roy 5ย years, 3ย months ago (8638684)
- 1 answers
Yogita Ingle 5ย years, 3ย months ago (2577571)
The story” A Letter to God: written by GL Fuentes enforces our faith in humanity. After reading the story, we know that there are still people who help others without any self-interest. Here the post master and other employees lay an example of humanity and kindness for others . First they all laughed at Lencho’s letter to God because they knew that there Was no such person but they were really moved by Lencho’s faith in God . They decided to help him to keep his faith alive and firm.Even though it was not possible for them to collect hundred pesos and kept them in an envelope for Lencho. They signed on it ‘God’ except there own name .This act shows us the true picture of humanity and motivates us to be a noble and kind person.
Posted by Sakshi Priya 5ย years, 3ย months ago (8501306)
- 1 answers
Meghna Thapar 5ย years, 3ย months ago (6237)
As hibiscus flower contains the colour pigment anthocynanin, not only can it be used as a natural indicator, it can also be used to produce natural dye that is eco-friendly and safe on human skin. Acid-base indicators are chemicals used to determine whether an aqueous solution is acidic, neutral, or alkaline. Because acidity and alkalinity relate to pH, they may also be known as pH indicators. Examples of acid-base indicators include litmus paper, phenolphthalein, and red cabbage juice.
Posted by Sakshi Priya 5ย years, 3ย months ago (8501306)
- 3 answers
Vaibhavi Vande 5ย years, 3ย months ago (9649127)
Raj Kumar 5ย years, 3ย months ago (9872071)
Posted by Sakshi Priya 5ย years, 3ย months ago (8501306)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
: MODEM stands for MOdulator/DEModulator. It is a hardware device that enables a computer to send and receive information over telephone lines by converting the digital data used by your computer into an analog signal used on telephone lines and the converting back once received on the other end.
Posted by Juhi Tekam 5ย years, 3ย months ago (9673815)
- 1 answers
Posted by D.R.K Mishra 5ย years, 3ย months ago (8757032)
- 2 answers
Md Jeeshan 5ย years, 3ย months ago (9876519)
Aditya Singh 5ย years, 3ย months ago (8977302)
Posted by Silent King 5ย years, 3ย months ago (9281260)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
Given: โABC is an isosceles triangle in which AB = AC.
Side BA is produced to D such that AD = AB.
To Prove: ∠BCD is a right angle.
Proof: โต ABC is an isosceles triangle
∴ ∠ABC = ∠ACB ...(1)
โต AB = AC and AD = AB
∴ AC = AD
∴ In โACD,
∠CDA = ∠ACD
| Angles opposite to equal sides of a triangle are equal
⇒ ∠CDB = ∠ACD ...(2)
Adding the corresponding sides of (1) and (2), we get
∠ABC + ∠CDB = ∠ACB + ∠ACD
⇒ ∠ABC + ∠CDB = ∠BCD ...(3)
In โBCD,
∠BCD + ∠DBC + ∠CDB = 180°
| โต Sum of all the angles of a triangle is 180°
⇒ ∠BCD + ∠ABC + ∠CDB = 180°
⇒ ∠BCD + ∠BCD = 180°
| Using (3)
⇒ 2∠BCD = 180°
⇒ ∠BCD = 90°
⇒ ∠BCD is a right angle.
Posted by Abhir Shrivastava 5ย years, 3ย months ago (9805806)
- 5 answers
Posted by Nikita Nikita 5ย years, 3ย months ago (9738480)
- 0 answers
Posted by Ayush Kapoor 5ย years, 3ย months ago (9876161)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
Most people tend to be very critical of political parties. They tend to blame parties for all that is wrong with our democracy and our political life. Parties have become identified with social and political divisions.
Posted by Aashi Singh 5ย years, 3ย months ago (9845164)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
Colloidal solutions of gold prepared by different methods are of different colours because of different diameters of colloidal gold particles. The colour of colloidal solutions depends upon the size of the colloidal particles.
Posted by Kirti Kirti 5ย years, 3ย months ago (9876174)
- 3 answers
Posted by Aakanksh Panicker 5ย years, 3ย months ago (9876187)
- 0 answers
Posted by Ayush Kapoor 5ย years, 3ย months ago (9876161)
- 1 answers
Yogita Ingle 5ย years, 3ย months ago (2577571)
Political Parties are the organized group of people whose main aim is to contest elections,come to power and retain power. It is said that parties reflect social and political divisions in the society through the following ways:
a. Parties divide the society on the basis of ideologies that its supports and endorses.
b. Parties involve partisanship where people show affiliation to a particular party and its ideology.
c. A party seeks to promote and upholds a particular interest. For example regional parties, caste based parties.
d. A party comprises of a leader who is actively propagating his/her party's programme and beliefs, active members who are associated with it and followers who believe in its programmes.
e. Parties tend to divide people for instance , caste based parties creates division in terms of pro reservation and anti reservation group.
f. Then there are regional based parties which may at times demand greater autonomy or even secessionism from the Union,laeding to balkanisation of the country.
g. As the political parties put forward their manifestos, the people decide to support different parties and they get divided. Thus political parties create social and political divisions
Posted by Dhruva Panchal 5ย years, 1ย month ago (9869775)
- 5 answers
Posted by Arav Gupta 5ย years, 3ย months ago (9666373)
- 0 answers
Posted by Chhavi Pahwa 5ย years, 3ย months ago (9295144)
- 1 answers
Kiran Kaur 5ย years, 3ย months ago (9803328)
Posted by Preeti Kumari 5ย years, 3ย months ago (9286675)
- 1 answers
Toshank Srivastava 5ย years, 2ย months ago (9755168)
Posted by Dgf Chd 5ย years, 3ย months ago (4635669)
- 1 answers
Gaurav Seth 5ย years, 3ย months ago (2898529)
Laboratory Preparation of Nitric Acid
In the laboratory, nitric acid can be prepared by heating sodium or potassium nitrate with concentrated sulphuric acid to about 423-475 K.
NaNO3 + H2SO4 ——> NaHSO4 + HNO3
Anhydrous nitric acid can be obtained by distillation of concentrated aqueous nitric acid with P4010.
Manufacture of Nitric Acid
Nitric acid is commonly manufactured by Ostwald process in which it is prepared by the catalytic oxidation of ammonia by atmospheric oxygen. The reaction is carried out at about 500 K and 9 x 105 Pa (9 bar) pressure in the presence of Pt or Rh gauge as catalyst.
4NH3(g) + 502(g)——> 4NO(g) + 6H20(g) ΔH =- 90.2 kJ
Pt/Rh gauge, 500K, 9 bar
Nitric oxide thus formed combines with oxygen to form nitrogen dioxide.
2NO(g) + O2 (g) ——> 2 NO2 (g)
Nitrogen dioxide so formed, dissolves in water to give nitric acid.
3NO2 (g) + H2O(l) —–> 2HNO3(aq) + NO(g)
Dilute nitric acid is further concentrated by dehydration with concentrated sulphuric acid to get about 98% acid.
Properties of Nitric Acid
Physical Properties
<div class="code-block code-block-20" style="text-align:start; -webkit-text-stroke-width:0px; margin:8px 0px"> </div>
1) Pure nitric acid is a colourless liquid.
2) It has boiling point 355.6 K and freezing point 231.4 K.
3) laboratory grade nitric acid contains about 68% of HNO3 by mass and has a specific gravity of 1.504.
4) The impure acid is generally yellow due to the presence of nitrogen dioxide as impurity. Nitric acid containing dissolved nitrogen dioxide is known as fuming nitric acid.
5) It has a corrosive action on skin and produces painful blisters.
Chemical Properties
(1) Acidic character: It is one of the strongest acids because it is highly ionised in aqueous solution giving hydronium and nitrate ions.
2HNO3(aq) +H2O (l) ——> H3O+ + NO3¯(aq)
It turns blue litmus red. It forms salts with alkalies, carbonates and bicarbonates.
NaOH + HNO3 —-> NaNO3 + H2O
Na2CO3 + HNO3 —-> 2NaNO3 + H2O + CO2
NaHCO3 + HNO3 —-> NaNO3 + H2O + CO2
(2) Action on metals: With the exception of gold and platinum, nitric acid attacks all metals forming a variety of products. The product depends upon the nature of metal, the concentration of acid and temperature.
(A) Metals that are more electropositive than hydrogen (Mg, Al, Mn, Zn, Fe, Pb, etc.). In this case nascent hydrogen is liberated which further reduces nitric acid.
M + 2HNO3 ——> M(NO3)2 + 2H
HNO3 + H —-> Reduction product + H2O
The principal product is NO2, with conc. HNO3, N2O with dil. HNO3, and ammonium nitrate with very dil. HNO3.
For example: Zn reacts as:
Laboratory Preparation of Nitric Acid
In the laboratory, nitric acid can be prepared by heating sodium or potassium nitrate with concentrated sulphuric acid to about 423-475 K.
NaNO3 + H2SO4 ——> NaHSO4 + HNO3
Anhydrous nitric acid can be obtained by distillation of concentrated aqueous nitric acid with P4010.
Manufacture of Nitric Acid
Nitric acid is commonly manufactured by Ostwald process in which it is prepared by the catalytic oxidation of ammonia by atmospheric oxygen. The reaction is carried out at about 500 K and 9 x 105 Pa (9 bar) pressure in the presence of Pt or Rh gauge as catalyst.
4NH3(g) + 502(g)——> 4NO(g) + 6H20(g) ΔH =- 90.2 kJ
Pt/Rh gauge, 500K, 9 bar
Nitric oxide thus formed combines with oxygen to form nitrogen dioxide.
2NO(g) + O2 (g) ——> 2 NO2 (g)
Nitrogen dioxide so formed, dissolves in water to give nitric acid.
3NO2 (g) + H2O(l) —–> 2HNO3(aq) + NO(g)
Dilute nitric acid is further concentrated by dehydration with concentrated sulphuric acid to get about 98% acid.
Properties of Nitric Acid
Physical Properties
<div class="code-block code-block-20" style="text-align:start; -webkit-text-stroke-width:0px; margin:8px 0px"> </div>
1) Pure nitric acid is a colourless liquid.
2) It has boiling point 355.6 K and freezing point 231.4 K.
3) laboratory grade nitric acid contains about 68% of HNO3 by mass and has a specific gravity of 1.504.
4) The impure acid is generally yellow due to the presence of nitrogen dioxide as impurity. Nitric acid containing dissolved nitrogen dioxide is known as fuming nitric acid.
5) It has a corrosive action on skin and produces painful blisters.
Chemical Properties
(1) Acidic character: It is one of the strongest acids because it is highly ionised in aqueous solution giving hydronium and nitrate ions.
2HNO3(aq) +H2O (l) ——> H3O+ + NO3¯(aq)
It turns blue litmus red. It forms salts with alkalies, carbonates and bicarbonates.
NaOH + HNO3 —-> NaNO3 + H2O
Na2CO3 + HNO3 —-> 2NaNO3 + H2O + CO2
NaHCO3 + HNO3 —-> NaNO3 + H2O + CO2
(2) Action on metals: With the exception of gold and platinum, nitric acid attacks all metals forming a variety of products. The product depends upon the nature of metal, the concentration of acid and temperature.
(A) Metals that are more electropositive than hydrogen (Mg, Al, Mn, Zn, Fe, Pb, etc.). In this case nascent hydrogen is liberated which further reduces nitric acid.
M + 2HNO3 ——> M(NO3)2 + 2H
HNO3 + H —-> Reduction product + H2O
The principal product is NO2, with conc. HNO3, N2O with dil. HNO3, and ammonium nitrate with very dil. HNO3.
Uses of Nitric Acid
(i) It is used in the manufacture of ammonium nitrate for fertilizers.
(ii) It is used in the manufacture of sulphuric acid by lead chamber process.
(iii) It is used in the manufacture of explosives such as trinitro toluene (TNT), nitroglycerine, picric acid, etc.
(iv) It is used in the manufacture of dyes, perfumes and silk.
(v) It is used for the manufacture of nitrates for use in explosive and pyrotechnics.
(vi) It is used in picking of stainless steel and etching of metals.
(vii) It is also used as an oxidiser in rocket fuels.
(viii) It is used in the purification of gold and silver as aqua regia.
Posted by Dgf Chd 4ย years, 8ย months ago (4635669)
- 1 answers
Sia ? 4ย years, 8ย months ago (6945213)
This is a simulation of the Brownian motion of a big particle (dust particle) that collides with a large set of smaller particles (molecules of a gas) which move with different velocities in different random directions.
Posted by Mehal Khunti 5ย years, 3ย months ago (9168608)
- 4 answers
Rahul Kumar 5ย years, 3ย months ago (9843154)
Posted by Mehal Khunti 5ย years, 3ย months ago (9168608)
- 2 answers
Athrav Raj 5ย years, 3ย months ago (9882143)
Gaurav Seth 5ย years, 3ย months ago (2898529)
A homophone is a word that is pronounced the same (to varying extent) as another word but differs in meaning. ...
Example:
The two words may be spelled the same, as in rose (flower) and rose (past tense of rise), or differently, as in rain, reign, and rein.
Know and No
myCBSEguide
Trusted by 1 Crore+ Students
Test Generator
Create papers online. It's FREE.
CUET Mock Tests
75,000+ questions to practice only on myCBSEguide app
Deepak Kumar 5ย years, 3ย months ago (9863491)
4 Thank You