Chemistry

Chemical Reactions and Processes

571 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 metals reaction of metals reactions of metals chemical properties of metals

Which one of these gas is released when Na reacts with cold water?

  1. $H _2$
  2. $Cl _2$
  3. $O _2$
  4. $H _2O$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reaction of 'Na' with cold water. 

$ 2Na+H _{2}O\rightarrow Na _{2}O+H _{2} \uparrow $
               The reaction stops with forming $ Na _{2}O $ . Because, we used cold water. The reaction doesnt continue to form NaOH.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

Potassium's reaction with water produces hydrogen gas of 

  1. bluish pink.

  2. greenish blue.

  3. orange.

  4. light pink.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Potassium's reaction with water produces hydrogen gas of bluish pink.
Potassium reacts with cold water and gives potassium hydroxide and hydrogen gas.
$\displaystyle 2K + 2H _2O \rightarrow 2KOH + H _2$
The reaction is exothermic and the resulting solution is basic.
The reaction is so vigorous that the evolved hydrogen catches fire spontaneously.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

Sodium in water catches fire due to formation of,

  1. hydrogen gas and evolution of heat.

  2. nitrogen gas and evolution of heat.

  3. hydrogen gas and absorption of heat.

  4. sulfur gas.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Sodium in water catches fire due to formation of hydrogen gas and evolution of heat.
$\displaystyle 2Na + 2H _2O \rightarrow 2Na^+ + 2OH^- + H _2 \uparrow$
Note: In exothermic process, heat is released. The reaction of Na with water is highly exothermic. Due to rapid increase in temperature, hydrogen gas catches fire.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

The reaction of potassium and water is ______ in nature.

  1. endothermic

  2. exothermic

  3. electron donating

  4. electron withdrawing
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The reaction of potassium and water is  exothermic in nature.
Potassium explosively reacts with water to form KOH with evolution of hydrogen gas.
$\displaystyle 2K + 2H _2O \rightarrow 2K^+ + 2OH^- + H _2 \uparrow$
Note: In exothermic process, heat is released. When KOH is added to water, the temperature of resulting solution rapidly increases.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

Calcium reacts __________ with water and forms calcium hydroxide and liberates hydrogen gas.

  1. vigroushly

  2. slowly

  3. violently

  4. uniformally
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Calcium reacts vigorously even with cold water and forms calcium hydroxide and liberates hydrogen gas.
$\displaystyle Ca+2H _2O \rightarrow Ca(OH) _2 + H _2 \uparrow$
Hence, the option (A) is the correct answer.

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

Metals react with cold water and gives

  1. metal oxide

  2. metal oxide and oxygen

  3. metal oxide and hydrogen

  4. metal hydroxide and hydrogen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Metals react with cold water and gives metal hydroxide and hydrogen.
For example, sodium reacts with cold water and gives sodium hydroxide and hydrogen gas.
$\displaystyle 2Na + 2H _2O \rightarrow 2NaOH + H _2$

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

An alkali metal $A$ gives a compound $B$ (molecular mass $=40$) on reacting with water. The compound $B$ gives a soluble compound $C$ on treatment with aluminium oxide. Metal $A$ is:

  1. $Al$
  2. $K$
  3. $Na$
  4. $Mg$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Alkali metal $(A)$ is sodium ($Na$) which forms $NaOH$ (compound $B$) with water .The reaction can be written as:
$2Na + 2H _{2}O \rightarrow  2NaOH + H _{2}$
$NaOH$ reacts with aluminium oxide($ Al _{2}O _{3}$) to form sodium aluminate (compound $C$) with chemical formula $NaAlO _{2}$.The reaction can be written as:
$Al _{2}O _{3} + 2NaOH \rightarrow  2NaAlO _{2} + H _{2}O$

Multiple choice chemistry metals reaction of metals reactions of metals chemical properties of metals

$Zn + H _{2}O$ (steam) $\longrightarrow  A + B$


In the equation, A and B are :

  1. $Zn$ and $H _2$
  2. $ZnH _{2}$ and $O _{2}$
  3. $ZnO _{2}$ and $H _{2}$
  4. $ZnO$ and $H _{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Zinc only when heated replaces hydrogen from steam thus forming oxides.

$Zn(s) +H _{2}O(g) \xrightarrow[\text{Above}\; 400^oC]{\Delta} ZnO(s)+H _2(g)$ .

Thus, the compounds A and B are $ZnO$ and $H _2$.

Multiple choice chemistry metals effects of oxidation reactions in daily life corrosion of metals electroplating and its application

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Which among the following is (are) true about slaking of lime?
(i) It is an endothermic reaction
(ii) It is an exothermic reaction
(iii) The pH of the resulting solution will be more than seven
(iv) The pH of the resulting solution will be less than seven

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i) and (iv)

  4. (iii) and (iv)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Slaking, the process of turning the traditional building material lime from calcium oxide (burnt lime or quicklime) into calcium hydroxide (slaked lime, slack lime, limewater, pickling lime or hydrated lime).
Its exothermic process and as calcium hydroxide is basic so pH will be greater than 7.

Multiple choice chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

The solution which liberates sulphur dioxide gas, from sodium sulphite :

  1. Sodium hydroxide solution

  2. A weak acid

  3. Dilute sulphuric acid

  4. hydrochloric acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Sodium sulphite reacts with dilute sulphuric acid in the manner shown below:
$Na _2SO _3(s) + H _2SO _4(l) \rightarrow Na _2SO _4 + SO _2(g) + H _2O$ 
So, $SO _2$ is liberated as a product in the above reaction.
Multiple choice chemistry nitrogen and sulfur sulfur and its oxides acid deposition natural resources- air, water and land

Sinks can _____ excess amount of sulphur dioxide.

  1. Produce

  2. Breakdown

  3. Absorb

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

Sources of $SO _2$ include fossil fuel combustion by industry, biomass burning, volcanic release and the oxidation of dimethylsulphide (DMS) from the oceans. Major SO2 sinks are oxidation by OH and deposition onto wet surfaces. Sinks are the areas that can absorb excess amounts thus reducing its abundance in the environment.

Multiple choice chemistry nitrogen and sulfur ammonia and fertilizers preparation of ammonia-laboratory method and haber's process ammonia

Calcium imide on hydrolysis will give gas (B) which on oxidation by bleaching powder gives gas (C). Gas (C) on reaction with magnesium gives compound (D). (D) on hydrolysis gives again gas (B). (B), (C) and (D) respectively are :

  1. ${NH _3}$, ${N _2}$, ${Mg _3N _2}$
  2. ${N _2}$, ${NH _3}$, $Mg _3N _2$
  3. ${N _2}$, ${N _2O _5}$, ${Mg(NO _3) _2}$
  4. ${NH _3}$, ${NO _2}$, ${Mg(NO _2) _2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Reactions :
$CaNH+H _2O\rightarrow CaO+NH _3$
$3CaOCl _2 + 2NH _3\rightarrow 3CaCl _2 + 3H _2O + N _2$
$3Mg + N _2 \rightarrow Mg _3N _2$
$Mg _3N _2 + 6 H _2O \rightarrow 3Mg(OH) _2 + 2NH _3$