Chemistry

Solutions and pH Chemistry

451 Questions

Solutions and pH chemistry focus on the acidity or alkalinity of various substances, from human urine to acidic soils. Questions involve titration calculations, molarity determination, and understanding mole fractions. This topic is a staple in the chemistry sections of state and national level competitive exams.

Calculating solution molarityMole fraction calculationpH value interpretationAcidic soils and pHTitration and neutralization

Solutions and pH Chemistry Questions

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

${ H } _{ 3 }{ PO } _{ 4 }$ is a tribasic acid and one of its salt is ${ NaH } _{ 2 }{ PO } _{ 4 }$ What volume of $1M\quad NaOH$ solution should be added to $12g\ { NaH } _{ 2 }{ PO } _{ 4 }$ to convert it into ${ Na } _{ 3 }{ PO } _{ 4 }$? ($at.wt$ of $P=31$)

  1. $100\ ml$
  2. $200\ ml$
  3. $80\ ml$
  4. $300\ ml$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Na{ H } _{ 2 }{ PO } _{ 4 }+NaOH\rightarrow { Na } _{ 2 }{ HPO } _{ 4 }+{ H } _{ 2 }O\quad \quad -(i)$

Moles$=\cfrac { 12 }{ 120 } $    $\cfrac { 12 }{ 120 } $            $\cfrac { 12 }{ 120 } $
${ Na } _{ 2 }{ HPO } _{ 4 }+NaOH\rightarrow { Na } _{ 3 }{ PO } _{ 4 }+{ H } _{ 2 }O\quad \quad \quad -(ii)$
Moles$=\cfrac { 12 }{ 120 } $     $\cfrac { 12 }{ 120 } $           $\cfrac { 12 }{ 120 } $
Moles of $NaOH$ required $=\cfrac { 12 }{ 120 } +\cfrac { 12 }{ 120 } $
                                              $=0.2$ moles
Now, $Mularity=\cfrac { Moles }{ Vol.of\quad sol\quad in\quad ltrs } $
$\therefore $ Volume of $NaOH$ solution $=\cfrac { 0.2 }{ 1 } $
                                                  $=0.2$ litres
                                                  $=200$ml

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Degree of hydrolysis for a salt of weak acid and strong base can be changed by 

  1. Increasing concentration of salt

  2. Increasing temperature

  3. Adding base

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The degree of hydrolysis (h) for a salt of a weak acid and strong base is given by h = sqrt(Kh / C). It depends on the hydrolysis constant (Kh), which is temperature-dependent, and the concentration (C).

Multiple choice chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

Aqueous solution of sodium acetate is :

  1. neutral

  2. weakly acidic

  3. strongly acidic

  4. alkaline
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sodium acetate is the sodium salt of acetic acid. Acetic acid reacts with sodium carbonate or sodium hydroxide to form a basic solution of sodium acetate which acts as buffer with acetic acid.

Multiple choice botany adaptation plant adaptation adaptation in plants plant habitat importance and classification of angiosperms aquatic plant adaptations pollination through water life in water

Most animals and plants can grow with pH, between

  1. 4 and 9

  2. 5 and 9

  3. 6 and 9

  4. 7 and 9
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Most plants and animals have evolved to thrive within a relatively neutral pH range, typically between 5 and 9, as extreme acidity or alkalinity interferes with biological processes.

Multiple choice economics environmental economics acid rain air pollution - effects and control air pollution and its effects

Rain is called as acid rain when its pH is below

  1. 7

  2. 6.5

  3. 6

  4. 4 to 5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Acid rain is a rain that is acidic, meaning it has very low pH. When sulfur dioxide and nitrogen oxides are released into the air, they react with water and oxygen and produces sulfuric and nitric acids. These acids then mix with water and result in acid rain. Normal rain water is slightly acidic with a pH range of 5-6. When the pH level of rain water falls below this range, it becomes acid rain. It can have harmful effects on plants, aquatic animals and infrastructure. 

Thus, the correct answer is option D.

Multiple choice economics environmental economics acid rain air pollution - effects and control air pollution and its effects

In acid rain, $SO _2$, sulphuric acid accounts for

  1. $100\%$
  2. $30\%$
  3. $50\%$
  4. $70\%$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Acid rain is caused by a chemical reaction. Basically, rain that has unusually low pH is called acid rain. The most common chemicals that cause acid rain are sulphur oxides and nitric oxides. These substances rise high in the atmosphere where they react with water, oxygen and other chemicals to form more acidic pollutant. Sulphur dioxide on reaction with water and oxygen forms sulphur trioxide which is rapidly converted into sulphuric acid in presence of water. It accounts for 70% volume in acid rain.

Hence, the correct answer is '70%'.

Multiple choice chemistry chemical changes electrochemical reactions electrolysis and its applications electrolytic cells and electrolysis

3%solution of glucose is isotonic with 1% solution of a non-volatile non-electrolyte substance the molecular mass of the substance would be 

  1. 30

  2. 60

  3. 90

  4. 120
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

since the two solution are isotonic,

therefore, $C _1 RT = C _2 RT$
$C _1 = C _2$
let  mass of solution = 100 g
so mass of glucose = 3g
and mass of non-volatile substance = 1g
so, we get
$\dfrac{3}{180} = \dfrac{1}{M}$
$M = 60$
hence, molecular mass of non-volatile substance = 60

Multiple choice evs - i busy at work - our internal organs human lymphatic system lymph and its function lymph and tissue fluid experiments on digestive enzymes role of receptors in the mouth types of teeth introduction to human digestive system circulatory system and organs

Amount of water in enamel is

  1. 90 - 92%

  2. 75 - 80%

  3. 40 - 50%
  4. $\approx $ 3%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enamel is the hardest material of animal kingdom. Enamel is ectodermal. It is secreted by Ameloblast cells of the ectoderm. lt has maximum amount of inorganic salt (96%) in It. Inorganic salt are mainly found in the form of phosphate and carbonate of Ca, Mg, Na and K. 3% of water is found in the enamel. Along with it Keratin and  ossein are also found in teeth. Ossein is a protein of bones, remaining part of tooth develops from mesoderm of embryo.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

On passing one friday of electric charge through a dilute solution of an acid, the volume of hydrogen obtained at S.T.P. is :

  1. 22400 ML.

  2. 1120 mL

  3. 2240 mL

  4. 11200 ML.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

One Faraday (96500 C) of charge deposits or releases 1 gram equivalent of a substance. For H2 gas (n=2), 1 Faraday releases 0.5 moles of H2. Volume at STP = 0.5 * 22400 mL = 11200 mL.

Multiple choice chemistry chemical changes applications of electrolysis electroplating extraction of metals by electrolysis

A current of  $13.4\mathrm { A }$  is passed through  $1.0\mathrm { L }$  of  $1.0\mathrm { M }$  $HCl$  solution by using  $Pt$  electrodes for  $1.0\  \mathrm { hr }.$  The  $pH$  of the solution after the experiment is over at  $298 K$  will be about.

  1. $0.20$
  2. $0.30$
  3. $0.40$
  4. $0.50$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$ (B) 0.30 $ 
Change in coulombs $ = 13.4\times 1\times 60\times 60 = 48240 $

Moles of electric charge $ = \dfrac{48240}{96500} = 0.5 F $

Equivalent of HCl decomposed on electrolysis $ = 0.5 $

Mili equivalents of HCl along electrolysis $ = 500 $

Molarity of HCl after electrolysis $ = \dfrac{500}{1000} = 0.5 M$

$ [H ^{+}] = 5\times 10^{-1} $

$ p{H} = -\log [H^{+}] $

$ p{H} = -\log 5\times 10^{-1} = 0.30. $
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which has maximum pH in aqueous solution ? 

  1. $NaClO$
  2. $NaClO _2$
  3. $NaClO _3$
  4. $NaClO _4$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$NaClO$ has the maximum $pH$ because the acidic strength decreases with decreasing $O$ atoms in oxy acids . Since $NaClO$ has the lowest oxygen atom among given options, it will have least acidic strength and hence, a maximum $pH$.