Chemistry

Chemical Reactions and Processes

626 Questions

Chemical reactions and processes questions cover the transformation of substances through electrolysis, thermal decomposition, and catalysis. Key areas include identifying gas evolution, balancing chemical equations, and understanding industrial chemical applications. This general chemistry topic is a staple in the science sections of multiple competitive examinations.

Thermal decompositionElectrolysis processGas evolution reactionsHeterogeneous catalystsFuel cell components

Chemical Reactions and Processes Questions

Multiple choice chemistry acids and alkalis acids with carbonates reactions of acids and bases properties of acids and bases

When an acid reacts with a metal carbonate or metal hydrogen carbonate, it gives the corresponding salt, gas and product. Name the gas and product?

  1. Carbon dioxide, Water

  2. Carbon dioxide, Salt

  3. Hydrogen, Salt

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acid + Metal carbonate  $\longrightarrow$ Salt + Water + Carbon dioxide

CaCO$ _3$ (calcium carbonate-metal carbonate) + 2HCl $\longrightarrow$ CaCl$ _2$ (calcium chloride-salt) + H$ _2$O + CO$ _2$

Multiple choice chemistry states of matter: gaseous and liquid states gay lussac's law gas laws states of matter

For which of the following reactions, is Gay Lussac's law not applicable?

  1. Formation of $HI$ from its constituents
  2. Formation of $NH _3$ from its constituents
  3. Formation of $CO _2$ from its constituents
  4. Formation of $SO _3$ from $SO _2$ and $O _2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gay Lussac's law not applicable to formation of $CO _{2}$ from its constituents as carbon and oxygen exist in different physical states.

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

The hydride ion, $H^{-}$ is a stronger base than its hydroxide ion $OH^{-}$. Which of the following reactions will occur, if sodium hydride $(NaH)$ is dissolved in water?

  1. $H^{-} _{\left ( aq \right )}+H _{2}O\rightarrow H _{3}O^{-}$
  2. $H^{-} _{\left ( aq \right )}+H _{2}O _{\left ( l \right )}\rightarrow OH^{-}+H _{2}$
  3. $H^{-}+H _{2}O _{(l)}\rightarrow\ no\ reaction$
  4. $None\ of\ the\ above$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sodium hydride $(NaH)$ react with water to form hydrogen gas and the sodium hydroxide $(NaOH)$.
$NaH+H _2O\rightarrow H _2+NaOH$
i.e., $Na^+, H^-$ and $H^+, OH^- $ give rise to $H _2$ and $NaOH$. So, it is similar to option B.

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Which of the following metals directly combine with hydrogen gas to give a hydride? 

  1. Au

  2. Ni

  3. Ca

  4. Cu
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Amongst, $Au$, $Ni$, $Ca$ and $Cu$, $Ca$ is the most reactive metal. So it easily combines with $H _2$ to form hydride while the other metals do not combine directly.


The reaction can be given as:-
$Ca+H _2\longrightarrow CaH _2$

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Non-stoichiometric hydrides are produced by:

  1. palladium, vanadium

  2. manganese, lithium

  3. nitrogen, filorine

  4. carbon, nockel
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The hydrogen deficient compounds formed by the reaction of $d-block$ and $f-block$ elements with dihydrogen are called Non-stoichiometric compounds. 

The d-block and f-block element form non-stoichiometric hydride because of the vacant d- and f-orbitals along with the small size.
Their elemental composition proportions cannot be represented in integers. They disobey the law of constant composition. Among the elements given, only vanadium and palladium form non-stoichiometric hydrides.


Answer: (A) palladium, vanadium

Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Hydrogen is:

  1. electropositive

  2. electronegative

  3. both electropositive as well as electronegative

  4. neither electropositive nor electronegative
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Hydrogen is both electropositive as well as electronegative, as it forms hydrogen ion $H^+$ as well as hydride ion $H^-$.
Multiple choice hydrides hydrogen and its compounds hydrogen chemistry

Hydrogen readily combines with these elements?

  1. Na

  2. K

  3. Ca

  4. Zn
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

${ H } _{ 2 }$ easily reacts with $Na, Ca, K$ as they are highly reactive metals and are placed at the top of the reactivity series.

${ 2Na }+{ H } _{ 2 }\rightarrow 2NaH$
$2K+{ H } _{ 2 }\rightarrow 2KH$
$Ca+{ H } _{ 2 }\rightarrow CaH _2$.

Multiple choice applications of adsorption adsorption adsorption and colloids surface chemistry chemistry

Which of the following increase(s) the activation of a solid adsorbent?

  1. Polishing the surface of the solid adsorbent.

  2. Sub-dividing the solid adsorbent.

  3. Blowing superheated steam through the porous adsorbent.

  4. Adsorption at very low pressure.
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid, or dissolved solid to a surface.
Adsorption of gases on solids depends on the following factors:

1) Surface area of the adsorbent: Adsorption is surface phenomenon. The extent of adsorption is directly proportional to the surface area of adsorbent. Finely divided metals and porous solids like charcoal, silica gel etc. posses more surface area when compared with solid lumps. 

2) Effect of pressure: Extent of adsorption increases with an increase in equilibrium pressure.

3) Nature of the gas: Since physical adsorption is non-specific, every gas gets adsorbed on the surface of any solid. Under a given conditions of temperature and pressure, the easily liquefiable gases such as $NH _3, HCl$ and $SO _2$ are adsorbed more than the gases like $H _2, N _2$ and $CO$. The ease with which a gas can be liquefied is determined by its critical temperature, $T _c$. 

Polishing the surface of the solid adsorbent makes no effect on adsorption.

Multiple choice applications of adsorption adsorption adsorption and colloids surface chemistry chemistry

Which of the following is/are application(s) of adsorption?

  1. De-ionization of water

  2. Gas masks
  3. Hygroscopic nature of $CaCl _2$

  4. Heterogeneous catalysis
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation
Adsorption :
The phenomenon of attracting and retaining the molecules of a substance on the surface of a liquid or a solid resulting into a higher concentration of the molecules on the surface is called adsorption. As a result of adsorption, there is a decrease of surface energy. The process of removal of an adsorbed substance from the surface on which it is adsorbed is called desorption. It is the reverse of adsorption and can be brought about by heating or by reducing the pressure.

Adsorption finds extensive applications both in research laboratory and in industry. A few applications are discussed below:
In gas masks:
All gas masks are devices containing suitable adsorbent so that the poisonous gases present in the atmosphere are preferentially adsorbed and the air for breathing is purified.
In heterogeneous catalysis:
The action of certain solids as catalysts is best explained in terms of adsorption. The theory is called adsorption theory. According to this theory, the gaseous reactants are adsorbed on the surface of the solid catalyst. As a result, the concentration of the reactants increases on the surface and hence, the rate of reaction increases. The theory is also able to explain the greater efficiency of the catalyst in the finely divided state, the action of catalyst promoters and poisons.
In softening of hard water (De-ionization of water):
The use of ion exchangers for softening of hard water is based upon the principle of competing adsorption just as in chromatography. Hygroscopic nature of $CaCl _2$ is not related to adsorption.

Multiple choice applications of adsorption adsorption adsorption and colloids surface chemistry chemistry

Which of the following can adsorb largest volume of hydrogen gas?

  1. Finely divided platinum

  2. Finely divided nickel

  3. Colloidal solution of palladium

  4. Colloidal Hydroxide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Colloidal solution of palladium can adsorb largest volume of hydrogen gas as the surface area of palladium is maximum in its colloidal solution. Higher is the surface area of catalyst, larger will be the volume of hydrogen adsorbed.

Multiple choice chemistry phenomena around us changes and its classification types of changes classification of changes

Examples of slow reaction are:

  1. rusting of iron

  2. weathering of rocks

  3. neutralization of sodium hydroxide by hydrochloric acid

  4. formation of coal
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation
Reactions that take a while are slow reactions and those which occur within a few seconds are fast reactions. The rusting of iron, the fermentation of sugar into alcohol, the chemical weathering of rocks (breaking down of rocks), the photosynthesis process in plants, coal formation are slow reactions. Whereas neutralization reaction of a strong base like sodium hydroxide and strong acid like $HCl$ is a fast reaction.
option A,B,D are correct
Multiple choice chemistry chemical reactions of organic compounds commercially important alcohols - methanol methanol some commercially important alcohols uses of alcohols

Methanol is never stored in aluminium vessel because:

  1. it reacts with aluminium forming toxic gas

  2. it results in explosion

  3. it corrodes the the metal by destroying its oxide layer

  4. aluminium reduces methanol to methane
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aluminum and its alloys resist most alcohols, however, some alcohols like methanol can be very corrosive when  extremely dry, especially at elevated temperatures.

Multiple choice evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

What is the final product when oxygen and hydrogen are mixed in a test tube at room temperature?

  1. Hydrogen peroxide

  2. Water

  3. A base

  4. A zwitterion

  5. No reaction takes place
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The gas-phase oxidation of hydrogen has been extensively studied over a wide range of temperatures and pressures.


$H _2 + \dfrac {1}{2} O _2 \rightarrow H _2O$ ,$ \Delta H^o= -242 kj/mol$
$H _2(g) + \dfrac {1}{2}O _2(g) \rightarrow H _2O(g) $        $\Delta H^o = –242 kJ/mol$

This reaction does not take place at all when the two gases are simply mixed at room temperature. 

At temperatures around 500-600°C it proceeds quite smoothly, but when heated above 700° or ignited with a spark, the mixture explodes.

Hence the correct option is E.


Multiple choice chemistry study of compounds a. hydrogen chloride laboratory method of preparation of hydrochloric acid physical and chemical properties and uses of hydrochloric acid hydrogen chloride: occurrence, preparation, purification and identification

Select the correct statement among the following.

  1. Hydrogen chloride is prepared by passing chlorine gas through hot water

  2. Hydrogen chloride is produced by combination of moist hydrogen gas with chlorine in the presence of diffused sunlight

  3. Hydrogen chloride can't be produced in the dark

  4. Activated carbon is used as a catalyst in the synthesis of hydrogen chloride
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation
Hydrogen chloride is produced by a combination of moist hydrogen gas with chlorine in the presence of diffused sunlight. The reaction should be maintained in diffused but not in direct sunlight as it is an explosive reaction. And not even in dark as it is very slow (negligible). Activated carbon is used as a catalyst in the synthesis of hydrogen chloride.
Hence, options $B$ and $D$ are correct.