Since the atomic number of hydrogen is one which also points that hydrogen has a single electron in its atom, it is the first element that stands in the periodic table. Depending upon the electronic configuration, the placement of the elements is decided in the periodic table.

Although the positioning of hydrogen is a big question among scientists and researchers due to its properties when it loses an electron and forms a cation, it is similar to alkali metals. However, if the hydrogen gains an electron and becomes a uni-negative ion, it resembles halogens. Though it shows resemblance to alkali metals and halogens, it is way different than both.

Dihydrogen is a homonuclear diatomic molecule, a combination of two hydrogen atoms. Since hydrogen is placed at number one in the periodic table as it's the lightest element with an atomic weight of 1.008u, the dihydrogen is the lightest molecule whose molecular weight is 2.016 atomic mass units.

NCERT Solutions for Chapter 9 Hydrogen includes all questions and answers that are part of the CBSE textbook and previous year's questions to help students learn the concept of dihydrogen in detail. Our experts have curated these answers, which provide detailed descriptions about dihydrogen and applications of dihydrogen. So, if you're looking for an all-in-one solution in an easy-to-understand language, go for MSVGo NCERT Solutions for Chapter 9 Hydrogen.

Preparation of Dihydrogen

To help students be thorough about each concept regarding the preparation of dehydration, NCERT Solutions for Chapter 9 Hydrogen explains the step-by-step procedure for the preparation of dihydrogen. One of the popular ways which scientists follow for preparing dihydrogen is by reacting zinc with acid. The reaction results in zinc forming Zinc Sulphate.

The second popular method of preparing dihydrogen is by reacting zinc with alkaline. The combination of sodium and zinc gives rise to dihydrogen as the third element.

Properties of Dihydrogen

The following are the properties of dihydrogen- 

• At STP, dihydrogen is present in the gaseous form only. 
• The melting point of dihydrogen is -259.16 degrees celsius.
• The boiling point of dihydrogen is termed to be 20.271 on the Kelvins scale.
• The sound speed through gaseous dihydrogen is 1310 meters per second.

Also known as the anion of hydrogen, hydrides are hydrogen compounds with fewer electronegative elements. If the hydrogen reacts with any of the elements and forms the compound, the compound formed is known as hydrides. Further hydrides are divided into three major parts- 

•  Ionic or saline hydrides - Example: Nah, KH, CaH2, etc. 
• Covalent hydrides - Example: SiH4 (silane)
• Metallic hydrides - Example: Cadmium, TiH aluminum, magnesium, etc.

IUPAC Name	Hydride
Molecular Formula	H–
Molecular Weight	1.008 g/mol
Chemical Name	Hydrogen Anion

 

The next topic in class 11, hydrogen is water. Earth is covered with more than 70% of water; therefore, a glance of earth from space appears to be blue. This blue colour is water with the chemical formula H2O. Each molecule of water is made from two hydrogen atoms with one oxygen atom. Since mankind has existed on this planet, water has been a life-driving force needed in almost every task from housing activities to drinking, bathing, cooking, etc. Although water is distributed unevenly on the earth’s surface, it is present in various forms.

Properties of water- 

Chemical formula	H2O
Molar mass	18.01528(33) g/mol
Odour	None
Acidity (pKa)	13.995
Boiling point	99.98 °C (211.96 °F; 373.13 K)
Melting  point	0.00 °C (32.00 °F; 273.15 K)
Density	Solid: 0.9167 g/ml at 0 °C Liquid: 0.961893 g/mL at 95 °C 0.9970474 g/mL at 25 °C 0.9998396 g/mL at 0 °C
Vapour pressure	3.1690 kilopascals or 0.031276 atm
Basicity (pKb)	13.995
Refractive index(nD)	1.3330 (20°C)
Thermal conductivity	0.6065 W/m·K
Viscosity	0.890 cP

One of the simplest peroxides, hydrogen peroxide, is almost a colourless liquid (pale blue) used for safety. It is majorly used as a bleaching agent and as a disinfectant.

Hydrogen peroxide Chemical formula	H2O2
Molecular Weight/ Molar Mass	4.0147 g/mol
Density	1.05 g/cm3
Boiling Point	150.2 °C
Melting Point	-0.43 °C

Also known as deuterium oxide, heavy water is a compound that is a combination of oxygen and deuterium. The chemical formula of heavy water is D2O.

Properties of heavy water-

Heavy Water (Deuterium Oxide)	D2O
Molecular Mass	20.02 grams/mole
Density	1.107 g/mL
Dipole moment	1.87 D
Melting Point	3.82oC
Boiling Point	101.4oC

Students studying in class 11 must have come across the term dihydrogen. The last topic of chapter 9,  class 11, hydrogen, is dihydrogen as a Fuel. Dihydrogen is used as a fuel as it has a high heating value which delivers sufficient flame and improved ignition temperature. As dihydrogen is large in quantity, it is used as a fuel for commercial purposes. 

1- What are the uses of hydrogen Class 11? 

One of the most prominent uses of hydrogen is Ammonia synthesis. Also, it is used as rocket fuel when combined with oxygen.

2- What are the physical properties of hydrogen? 

The following are physical properties of hydrogen- 

• Hydrogen has the lowest density in all gases with no color or smell. 
• Hydrogen is termed clean gas and is helpful for the future, which emerges from the water and oxidises. 
• Hydrogen is present in abundance in the universe. 
• It can be produced from various sources and stored easily in large amounts. 
• Hydrogen was first generated in the early 16th century.

3- What are the benefits of Class 11 hydrogen?

The following are the advantages of hydrogen- 

• Hydrogen is a rich source of energy where there’s no possibility of running out. 
• Hydrogen can be produced easily through numerous sources 
• It is termed to be a clean gas for the future use 
• Hydrogen is a non-toxic gas which makes it environmentally friendly 
• When combined with oxygen to produce electricity or refill rockets, it significantly reduces pollution.