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

A water solution with a pH of 7

  1. is an acid

  2. is a base

  3. contains neither OH- nor H+

  4. has equal numbers of OH- and H+ ions
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A pH of 7 is neutral. In a neutral solution, the concentration of hydrogen ions (H+) is exactly equal to the concentration of hydroxide ions (OH-).

Multiple choice

A solution with a pH of 9

  1. is an acidic solution

  2. is an alkaline solution

  3. has more OH-ions than H+ ions

  4. both B and C
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A pH above 7 is alkaline (basic). In alkaline solutions, the concentration of OH- ions is greater than the concentration of H+ ions.

Multiple choice biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

Water above the dissolved $O _2$ content may be considered uncontaminated.

  1. $0.8$ mg/l
  2. $0.008$ mg/l
  3. $8.0$ mg/l
  4. 8 $\mu$g/l
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The microorganisms in water decompose organic matter using dissolved oxygen. More the amount of dissolved oxygen in the water, more is its purity and vice versa. Water below 5mg/l is considered contamined and water above 8mg/l is considered as uncontaminated.

So, the correct answer is "8.0mg/l".
Multiple choice chemistry planet earth acid deposition air and air pollution natural resources- air, water and land

Assertion(A) : Rainwater normally has a $pH$ $= $ 5.6


Reason (R) : This is due to the presence of $H _{2}SO _{4}$ and $HNO _{3}$ produced from oxides of sulphur and nitrogen.

  1. Both A and R are true and R is the correct explanation of A.

  2. Both A and R are true but R is not correct explanation of A.

  3. A is true and R is false.

  4. A is false and R is true
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Normal rain has a pH of about 5.6. This is because it reacts with carbon dioxide in the atmosphere and forms mildly acidic carbonic acid before it becomes rain.

Acid rains occur due to oxides of nitrogen and sulphur.

Nitric acid & sulphuric acid in the atmosphere dissolve in rainwater and come down to earth as acid rain. 

Acid rains have a pH 4.

Therefore, option C is correct

Multiple choice chemistry planet earth acid deposition air and air pollution natural resources- air, water and land

What is the pH of acid rain?

  1. 5.8

  2. 5.5

  3. 4.2

  4. 3.8
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides—produced from power plants and automobiles—the rain becomes much more acidic. Typical acid rain has a pH value of 4.0.
 A decrease in pH values from 5.0 to 4.0 means that the acidity is 10 times greater.
Multiple choice chemistry planet earth acid deposition air and air pollution natural resources- air, water and land

Over a number of years the average pH of a stream changes from a pH of 6.9 to a pH of 5.9 due to acid rain. Which statement is true about the pH of the stream?

  1. The pH of the stream now is one times more acidic than it was years ago

  2. The stream now has 10 times more hydroxide ions than it did years ago

  3. The pH of the stream is now 10 times more acidic than it was years ago

  4. The stream is more basic now than it was years ago

  5. The concentration of hydronium ion in the stream has decreased over the years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Over a number of years the average pH of a stream changes from a pH of 6.9 to a pH of 5.9 due to acid rain. The pH of the stream is now 10 times more acidic than it was years ago.
Years ago, the pH was 6.9. The present day pH is 5.9. The change in pH is
$\displaystyle  = \Delta pH= 5.9-6.9 = -1$
The corresponding change in hydrogen ion concentration is:
$\displaystyle 10^{-\Delta pH}= 10^{-(-1)} = 10$

Multiple choice

What should the pH of a "close up" Holstein's urine be?

  1. Between 2.0 and 3.0

  2. Between 1.0 and 3.0

  3. Between 6.0 and 6.5

  4. Between 11.0 and 12.0
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Monitoring urine pH in close-up cows is a standard practice to manage the risk of milk fever. A target pH range of 6.0 to 6.5 indicates that the dietary cation-anion difference (DCAD) program is effectively acidifying the cow's system.

Multiple choice chemistry water too little to waste pollution of water water pollution planet earth

10 mL of water required 1.47 mg of $K _{2}Cr _{2}O _{7}$ (M. wt. = 294) for oxidation of dissolved organic matter in presence of acid. Then the C.O.D of water sample is:

  1. 2.44 ppm

  2. 24 ppm

  3. 32 ppm

  4. 1.6 ppm
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$ Number \  of   \ milliequivalent $ = $\dfrac{weight \ in \ mg}{Equivalent\  weight}$


= $\dfrac{1.47}{294/6}$ = $0.03meq$

$\therefore$COD of sample is:

$\dfrac{0.03}{10}\times 1000$ =  $3meq/L$

In terms of Oxygen COD is :

$3 meq/L \times  (8 mg O _2/meq)$ = $24 mg/L= 24ppm$

Option B is correct.

Multiple choice bio-chemistry absorption by roots - the processes involved osmotic relations of plant cells transport across membrane imbibition and its importance

The value of $2, 4$-D is $25$ ppm. How many amount of $2, 4$-D should require for making its $5$ litres, $15$ litres and $25$ litres solutions respectively.

  1. $25$gm, $50$gm, $75$gm
  2. $50$gm, $175$gm, $525$gm
  3. $250$gm, $750$gm, $1250$gm
  4. $125$gm, $375$gm, $625$gm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

1 ppm is equal to 1 gm per litre.

25 ppm is equal to 25 gm per litre.
Therefore, 
for 5 litres, amount needed is 5 times 25= 125 gm
for 15 litres, amount needed is 15 times 25= 375 gm
for 25 litres, amount needed is 25 times 25= 625 gm.
So the correct option is D.