Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors which one is most important in this respect?
Why does $\mathrm{H}^{+}$ion always get associated with other atoms or molecules?
Metal hydrides are ionic, covalent or molecular in nature. Among LiH, $\mathrm{NaH}, \mathrm{KH}, \mathrm{RbH}, \mathrm{CsH}$, the correct order of increasing ionic character is
Which of the following hydrides is electron-precise hydride?
Radioactive elements emit $\alpha, \beta$ and $\gamma$ rays and are characterised by their half-lives. The radioactive isotope of hydrogen is
Consider the reactions
(i) $\mathrm{H}_2 \mathrm{O}_2+2 \mathrm{HI} \longrightarrow \mathrm{I}_2+2 \mathrm{H}_2 \mathrm{O}$
(ii) $\mathrm{HOCl}+\mathrm{H}_2 \mathrm{O}_2 \longrightarrow \mathrm{H}_3 \mathrm{O}^{+}+\mathrm{Cl}^{-}+\mathrm{O}_2$
Which of the following statements is correct about $\mathrm{H}_2 \mathrm{O}_2$ with reference to these reactions? Hydrogen peroxide is ........... .
The oxide that gives $\mathrm{H}_2 \mathrm{O}_2$ on treatment with dilute $\mathrm{H}_2 \mathrm{SO}_4$ is
Which of the following equations depict the oxidising nature of $\mathrm{H}_2 \mathrm{O}_2$ ?
Which of the following equation depicts reducing nature of $\mathrm{H}_2 \mathrm{O}_2$ ?
Hydrogen peroxide is ........... .
Which of the following reactions increases production of dihydrogen from synthesis gas?
When sodium peroxide is treated with dilute sulphuric acid, we get ............ .
Hydrogen peroxide is obtained by the electrolysis of .......... .
Which of the following reactions is an example of use of water gas in the synthesis of other compounds?
Which of the following ions will cause hardness in water sample?
Which of the following compounds is used for water softening?
Elements of which of the following group(s) of periodic table do not form hydrides?
Only one element of ........... forms hydride.
Assertion (A) Permanent hardness of water is removed by treatment with washing soda.
Reason (R) Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.
Assertion (A) Some metals like platinum and palladium, can be used as storage media for hydrogen.
Reason (R) Platinum and palladium can absorb large volumes of hydrogen.
Which of the following statements are not true for hydrogen?
Dihydrogen can be prepared on commercial scale by different methods. In its preparation by the action of steam on hydrocarbons, a mixture of CO and $\mathrm{H}_2$ gas is formed. It is known as ........... .
Which of the following statement(s) is/are correct in the case of heavy water?
Which of the following statements about hydrogen are correct?
Some of the properties of water are described below. Which of them is/are not correct?
Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of
Which of the following statements is correct?
Which of the following statements is correct?
Which of the following statements is correct?
How can production of hydrogen from water gas be increased by using water gas shift reaction?
What are metallic/interstitial hydrides? How do they differ from molecular hydrides?
Name the classes of hydrides to which $\mathrm{H}_2 \mathrm{O}, \mathrm{B}_2 \mathrm{H}_6$ and NaH belong.
If same mass of liquid water and a piece of ice is taken, then why is the density of ice less than that of liquid water?
Complete the following equations
(i) $\mathrm{PbS}(s)+\mathrm{H}_2 \mathrm{O}_2(a q) \longrightarrow$
(ii) $\mathrm{CO}(\mathrm{g})+2 \mathrm{H}_2(\mathrm{g}) \xrightarrow[\text { catalyst }]{\text { Cobalt }}$
Give reasons
(i) Lakes freeze from top towards bottom.
(ii) Ice floats on water.
What do you understand by the term 'auto-protolysis' of water? What is its significance?
Discuss briefly de-mineralisation of water by ion exchange resin.
Molecular hydrides are classified as electron deficient, electron precise and electron rich compounds. Explain each type with two examples.
How is heavy water prepared? Compare its physical properties with those of ordinary water.
Write one chemical reaction for the preparation of $\mathrm{D}_2 \mathrm{O}_2$.
Calculate the strength of 5 volumes $\mathrm{H}_2 \mathrm{O}_2$ solution.
(i) Draw the gas phase and solid phase structure of $\mathrm{H}_2 \mathrm{O}_2$.
(ii) $\mathrm{H}_2 \mathrm{O}_2$ is a better oxidising agent than water. Explain.
Melting point, enthalpy of vaporisation and viscosity data of $\mathrm{H}_2 \mathrm{O}$ and $\mathrm{D}_2 \mathrm{O}$ is given below
| H$$_2$$O | D$$_2$$O | |
|---|---|---|
| Melting point/K | 373.0 | 374.4 |
| Enthalpy of vaporisation at (373 K)/kJ mol$$^{-1}$$ | 40.66 | 41.61 |
| Viscosity/centipoise | 0.8903 | 1.107 |
On the basis of this data explain in which of these liquids intermolecular forces are stronger?
Dihydrogen reacts with dioxygen $\left(\mathrm{O}_2\right)$ to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.
Explain why HCl is a gas and HF is a liquid?
When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes autoionisation?
Rohan heard that instructions were given to the laboratory attendent to store a particular chemical, i.e., keep it in the dark room, add some urea in it, and keep it away from dust. This chemical acts as an oxidising as well as a reducing agent in both acidic and alkaline media. This chemical is important for use in the pollution control treatment of domestic and industrial effluents.
(i) Write the name of this compound.
(ii) Explain why such precautions are taken for storing this chemical.
Give reasons why hydrogen resembles alkali metals?
Hydrogen generally forms covalent compounds. Give reason.
Why is the ionisation enthalpy of hydrogen higher than that of sodium?
Basic principle of hydrogen economy is transportation and storage of energy in the form of liquid or gaseous hydrogen. Which property of hydrogen may be useful for this purpose? Support your answer with the chemical equation if required.
50 What is the importance of heavy water?
Write the Lewis structure of hydrogen peroxide.
An acidic solution of hydrogen peroxide behaves as an oxidising as well as reducing agent. Illustrate it with the help of a chemical equation.
With the help of suitable examples, explain the property of $\mathrm{H}_2 \mathrm{O}_2$ that is responsible for its bleaching action?
Why is water molecule polar?
Why does water show high boiling point as compared to hydrogen sulphide? Give reasons for your answer.
Why can dilute solutions of hydrogen peroxide not be concentrated by heating? How can a concentrated solution of hydrogen peroxide be obtained?
Why is hydrogen peroxide stored in wax lined bottles?
Why does hard water not form lather with soap?
Phosphoric acid is preferred over sulphuric acid in preparing hydrogen peroxide from peroxides. Why?
How will you account for $104.5^{\circ}$ bond angle in water?
Write redox reaction between fluorine and water.
Write two reactions to explain amphoteric nature of water.
Correlate the items listed in Column I with those listed in Column II. Find out as many correlations as you can.
| Column I | Column II | ||
|---|---|---|---|
| A. | Synthesis gas | 1. | $$\mathrm{Na_2[Na_4(PO_3)_6]}$$ |
| B. | Dihydrogen | 2. | Oxidising agent |
| C. | Heavy water | 3. | Softening of water |
| D. | Calgon | 4. | Reducing agent |
| E. | Hydrogen peroxide | 5. | Stoichiometric compounds of s-block elements |
| F. | Salt like hydrides | 6. | Prolonged electrolysis of water |
| 7. | Zn + NaOH | ||
| 8. | Zn + dil. H$$_2$$SO$$_4$$ | ||
| 9. | Synthesis of methanol | ||
| 10. | Mixture of CO and H$$_2$$ |
Match Column I with Column II for the given properties/applications mentioned therein.
| Column I | Column II | ||
|---|---|---|---|
| A. | H | 1. | used in the name of perhydrol. |
| B. | H$$_2$$ | 2. | can be reduced to dihydrogen by NaH. |
| C. | H$$_2$$O | 3. | can be used in hydroformylation of olefin. |
| D. | H$$_2$$O$$_2$$ | 4. | can be used in cutting and welding. |
Match the terms in Column I with the relevant item in Column II.
| Column I | Column II | ||
|---|---|---|---|
| A. | Electrolysis of water produces | 1. | atomic reactor |
| B. | Lithium aluminium hydride is used as | 2. | polar molecule |
| C. | Hydrogen chloride is a | 3. | recombines on metal surface to generate high temperature |
| D. | Heavy water is used in | 4. | reducing agent |
| E. | Atomic hydrogen | 5. | hydrogen and oxygen |
Match the items in Column I with the relevant item in Column II.
| Column I | Column II | ||
|---|---|---|---|
| A. | Hydrogen peroxide is used as a | 1. | zeolite |
| B. | Used in Calgon method | 2. | perohydrol |
| C. | Permanent hardness of hard water is removed by | 3. | sodium hexametaphosphate |
| 4. | propellant |
Atomic hydrogen combines with almost all elements but molecular hydrogen does not. Explain.
How can $\mathrm{D}_2 \mathrm{O}$ be prepared from water? Mention the physical properties in which $\mathrm{D}_2 \mathrm{O}$ differs from $\mathrm{H}_2 \mathrm{O}$. Give at least three reactions of $\mathrm{D}_2 \mathrm{O}$ showing the exchange of hydrogen with deuterium.
How will you concentrate $\mathrm{H}_2 \mathrm{O}_2$ ? Show differences between structures of $\mathrm{H}_2 \mathrm{O}_2$ and $\mathrm{H}_2 \mathrm{O}$ by drawing their spatial structures. Also mention three important uses of $\mathrm{H}_2 \mathrm{O}_2$.
(i) Give a method for the manufacture of hydrogen peroxide and explain the reactions involved therein.
(ii) Illustrate oxidising, reducing and acidic properties of hydrogen peroxide with equations.
(i) What mass of hydrogen peroxide will be present in 2 L of a 5 molar solution?
(ii) Calculate the mass of oxygen which will be liberated by the decomposition of 200 mL of this solution.
A colourless liquid ' $A$ ' contains H and 0 elements only. It decomposes slowly on exposure to light. It is stabilised by mixing urea to store in the presence of light.
(i) Suggest possible structure of $A$.
(ii) Write chemical equations for its decomposition reaction in light.
An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine. This is used in the synthesis of other useful hydrides. Write the formula of this hydride. Write its reaction with $\mathrm{Al}_2 \mathrm{Cl}_6$.
Sodium forms a crystalline ionic solid with dihydrogen. The solid is non-volatile and non-conducting in nature. It reacts violently with water to produce dihydrogen gas. Write the formula of this compound and its reaction with water. What will happen on electrolysis of the melt of this solid?